research activities ix research center for molecular-scale

IX-A-1 Photo Precursor for Pentacene

UNO, Hidemitsu1; YAMASHITA, Yuko2;KIKUCHI, Makoto2; WATANABE, Hikaru2;YAMADA, Hiroko2; OKUJIMA, Tetsuo2; OGAWA,Takuji3; ONO, Noboru2

(1Ehime Univ., JST; 2Ehime Univ.; 3IMS, JST)

[Tetrahedron Lett. 46, 1981–1983 (2005)]

Pentacene is one of the most sensational polycyclichydrocarbons, which draws attention from many fieldsdue to its high electron mobility. Many efforts havebeen focused on the device preparation of not onlypentacene itself but also its derivatives. For the applica-tion of pentacene and its derivatives, one of the biggestproblem is the low solubility in common solvents. Diffi-culties are often encountered in the puriffication of itsderivatives, and several manipulations of a high vacuumsublimation are required. In the final stage of pentacenebased devices, the vapor deposition technique underhigh vacuum is usually employed. In order to overcomethe problem, precursors, which give pentacene or itsderivatives by thermal decomposition, namely retroDiels-Alder reaction, were developed and their applica-tions for field effect transistors (FET) and organic thinfilm transistors (OTFT) were recently reported. In thesecases, retro Diels-Alder reaction of the precursors wasdesigned to proceed at rather low temperatures by extru-sion of tetrachlorobenzene and N-sulfinylacetamide. Therequisite for such leaving molecules is sufficiently smalland inert not to affect the property of pentacene devices.For these precursor methods, there is an inevitabledrawback that the high vacuum sublimation technique,one of the most reliable and successful device prepara-tion methods, cannot be applied, because the trigger ofthe precursors to pentacene is heat. We thought that notonly this shortcoming of the precursor method but alsoproperty of the leaving molecules can be dramaticallyimproved if the alternative physical decompositionmethod, namely light, is applied. In this communication,we report preparation of the first photo-convertibleprecursor to pentacene and its fundamental properties.

IX-A-2 Synthesis and Self-Assembly of NovelPorphyrin Molecular Wires

KAWAO, Masahiro1; OZAWA, Hiroaki2;TANAKA, Hirofumi3; OGAWA, Takuji3(1Ehime Univ., JST; 2SOKENDAI, JST; 4IMS, JST)

[Thin Solid Films in press (2005)]

Sub-micrometer long butadiyne-linked porphyrinwires were synthesized by oxidative coupling of di-ethynylporphyrin. The porphyrin wires were analyzedby analytical gel permeation chromatography, absorp-tion spectroscopy and matrix-assisted laser desorption/ionization time of flight mass spectroscopy. Observa-tions of the wire were performed by atomic forcemicroscopy. Self-assembled structures of the wires wereobserved on highly oriented pyrolytic graphite. Self-assembling features of the porphyrin wires depended onthe length of the porphyrin wires and the concentrationof the depositing solution.

Figure 1.

151Annual Review 2005

RESEARCH ACTIVITIES IXResearch Center for Molecular-Scale Nanoscience

IX-A Nano-Science and Nano-Technology toward MolecularScale Electronics

Molecular electronics is a fairly new and fascinating area of research that is firing the imagination of scientists.However, most single organic molecules are not conductive in a classical sense, long range electronic transportthrough single molecules can not be so effective to realize practical electronic circuits. Our group is interested in (1)construction of nano-structures made from conductive materials such as carbon nanotubes, metal particles or rods,with functional organic molecules, (2) measurements of electric or photonic properties of individual nano-structureswhile observing their nanometric images, and (3) conductance change of single molecules by external stimulationsuch as electric field, photon irradiation or chemical species.

200nm

Type B

Type A

50nm

(a)

(b)

IX-A-3 Molecular Junctions Composed ofOligothiophene Dithiol Bridged GoldNanoparticles Exhibiting PhotoresponsiveProperties

HUANG, Wei1; MASUDA, Gou2; MAEDA,Seisuke2; TANAKA, Hirofumi3; OGAWA, Takuji3(1Nanjin Univ.; 2Ehime Univ.; 3IMS, JST)

[Chem. Eur. J. 12, 607 (2006)]

Three oligothiophene dithiols with different numberof thiophene rings (3, 6 or 9) were synthesized andcharacterized. X-ray single crystal structures ofcompounds 3’,4’-dibutyl-5’5’’-dithiocyano-2,2’:5’,2’’-terthiophene (2) and 5,5’’’’’-dithiocyano-tetrabutyl-2,2’:5’,2’’:5’’,2’’’:5’’’,2’’’’:5’’’’,2’’’’’-hexathiophene(5) were involved herein to show the exact molecularlengths as well as the difference between their UV-visspectra arising from the different packing modes. Thesedithiols with different chain lengths were then treatedwith t-dodecanethiol protected active gold nano-parti-cles (Au-NPs) via in situ thiol-to-thiol ligand exchangein the presence of 1 µm gap Au-electrodes. Thus themolecular junctions composed of self-assembled filmswere prepared, where oligothiophene dithiol bridgedAu-NPs were attached to two electrodes by means ofAu–S bonded contacts. The morphologies and I-Vcharacteristics of these films were studied by SEM andAFM approaches, which suggest the thickness of thefilms varied within the size of one isolated Au-NPs andtypical distance dependent semiconductor propertiescould be observed. Current-voltage (I-V) measurementsfor these devices were performed where the films servedas active elements in the temperature range 6 ~ 300 Kand classical Arrhenius plots and their linear fittingswere carried out to give the activation energies (∆E).Furthermore, preliminary studies on the photorespon-sive properties of these junctions were explored at 80,160 and 300 K, respectively. Physical and photochemi-cal mechanisms were used to explain the possible pro-cesses. To the best of our knowledge, this is the firstreport where oligothiophene dithiols act as bridgingunits to link Au-NPs, and also the first report aboutfunctionalized Au-NPs exhibiting photo response prop-erties in the solid state.

Figure 1. (a) and (b) Tapping mode AFM topographies of theself-assembled film of 14 on the micro-gap gold electrodescorresponding to the areas marked in (c). (d) I-V curves withdifferent separations between cantilever and brass substrate byusing contacting mode AFM.

IX-A-4 Simple Preparation Method forSupramolecular Porphyrin Arrays on MicaUsing Air/Water Interface

SATO, Hirokazu1; TSUTSUMI, Osamu1; TAKEDA,Kazuyoshi1; TANAKA, Hirofumi2; OGAWA,Takuji2(1Ebara Research Co.; 2IMS, JST)

[Jpn. J. Appl. Phys. in press (2005)]

The fabrication of supramolecular porphyrin arrayson the surface of a mica substrate is demonstrated. Thesupramolecular structures are prepared at the air/waterinterface from a dilute solution of porphyrin dimer andbidentate ligand and then transferred to mica by usingthe conventional Langmuir-Blodgett method. Isolatedwire-like structures and networks of structures areobserved by atomic force microscopy. From the analysisof the height histogram and average width, these struc-tures are considered to be side-by-side arrangements ofsupramolecular chains of porphyrin dimer and bidentateligand. By changing the ligand molecule, we demon-strate that the configuration of the supramolecular struc-ture can be controlled.

IX-A-5 Novel Photochemical Synthesis ofPentacene and Its Derivatives

YAMADA, Hiroko1; YAMASHITA, Yuko1;KIKUCHI, Makoto1; WATANABE, Hikaru1;OKUJIMA, Tetsuo1; UNO, Hidemitsu2; OGAWA,Takuji3; OHARA, Keishi1; MUKAI, Kazuo1; ONO,Noboru1

(1Ehime Univ.; 2Ehime Univ., JST; 3IMS, JST)

[Chem. Eur. J. 11, 6212 (2005)]

A novel -diketone precursor of pentacene, 6,13-dihydro-6,13-ethanopentacene- 15,16-dione, was pre-pared and converted successfully to pentacene in 74%yield by photolysis of the precursor in toluene: Irradia-tion of the diketone solution in toluene with light of 460nm under an Ar atmosphere caused the solution tochange from yellow to fluorescent orange-pink within afew minutes, after which, purple precipitates appeared.After 35 min, the solution changed to colorless and thepurple precipitates were filtered to give pentacene in74% yield. By contrast, in the presence of oxygen, thecolor of the solution changed from yellow to pale yel-low, and only 6,13-endoperoxide of pentacene wasquantitatively obtained. The rate of the reaction uponphotolysis was measured by observing the decay of n-*absorption of the precursor at 460 nm, and was found tobe similar in both the presence and absence of oxygen.Therefore, the photoreaction of the -diketone precursorseemed to occur via the singlet excited state. Becausethe T-T absorption of pentacene was observed upon

152 RESEARCH ACTIVITIES IX Research Center for Molecular-scale Nanoscience

(a) (b)

(c) (d)

photolysis of the precursor in the nanosecond transientabsorption measurement under an Ar atmosphere, theexcited triplet state of the pentacene generated singletoxygen by sensitization, and it reacted with the ground-state pentacene to give the 6,13-endoperoxide. The -diketone deposited on glass was also converted success-fully to pentacene film by photoirradiation. In addition,diketone precursors of a mixture of 2,8- and 2,9-dibromopentacene and 2,6-trianthrylene were also pre-pared and their photoconversion was performed.

IX-A-6 Porphyrin Molecules Working asNanodevice on Single-Walled Carbon NanotubeWiring

TANAKA, Hirofumi1; YAJIMA, Takashi;MATSUMOTO, Takuya2; OTSUKA, Yoichi2;OGAWA, Takuji1(1IMS, JST; 2Osaka Univ., JST)

[Adv. Mater. in press]

For the future development of molecular electronics,we should construct nanosized molecular devices placedon nanowiring. To obtain high-quality devices com-posed of a few molecules, the wiring and the deviceshould be connected well to maintain a constant inter-face. For this purpose, a single-walled carbon nanotube(SWNT)/porphyrin complex was prepared and then itselectronic property was investigated while observing atopographic image using point-contact current imagingatomic force microscopy (PCI-AFM). Using PCI-AFM,we can measure the current along the long axis of thewiring by which the quality of the device in the circuitcan be determined. The I-V curves were asymmetricwith respect to the origin where an aggregate of severalporphyrin molecules was absorbed, while they weresymmetric without them. This means the porphyrinaggregation works as a rectification device on SWNTwiring. This is the first study which proves the electronproperty of a few porphyrin molecules absorbed onSWNT.

Figure 1. (a) Topographic image of BPP-Zn absorbed onSWNT electrode. The I-V measurement was performed atpoints A’-G’. (b) Cross section of each line in (a). (c) Relationbetween a tunnel resistance and a distance of sample andcantilever. (d) I-V curves obtained at each point. (e) The I-Vcurves were normalized at –1.5 V. All curves are coincidentbelow 0 V. I-V curves are classified into two types over 0 V.One is symmetrical with respect to the origin where porphyrinis absorbed and another is asymmetrical where no porphyrin isabsorbed. Two types of arrow indicate the band edges (BE) ofthe objects. Black and red arrows indicate the BE of the objectfor N-points and P-points, respectively.

IX-A-7 Electronic Properties of Single-WalledCarbon Nanotube/Porphyrin Polymer ComplexMeasured by Point-Contact Current ImagingAtomic Force Microscopy

TANAKA, Hirofumi1; YAJIMA, Takashi; KAWAO,Masahiro2; OGAWA, Takuji1(1IMS, JST; 2SOKENDAI, IMS)

[J. Nanosci. Nanotechnol. in press]

The electronic properties of a porphyrin polymerwire absorbed on a single-walled carbon nanotube(SWNT) were investigated. Current-voltage (I-V) curveswere measured simultaneously along with topographicobservations using point-contact current imaging atomicforce microscopy (PCI-AFM). I-V curves taken at thelocation of porphyrin polymer wire absorption wereasymmetric with respect to the origin, while they weresymmetric in the absence of a porphyrin polymer wire.The electron conduction mechanism of the porphyrin onthe SWNT was similar to the case of SWNT/ 5,15-Bis-pentylporphyrinato zinc(II) complex in our recent work.

IX-A-8 Preparation of Very Reactive Thiol-Protected Gold Nanoparticles: Revisiting theBrust-Schiffrin Method

ARAKI, Koiti1; MIZUGUCHI, Eisuke2; TANAKA,Hirofumi; OGAWA, Takuji(1SaoPaulo Univ.; 2Ehime Univ.)

[J. Nanosci. Nanotechnol. in press]

Metal nanoparticles have attracted great interest innanoscience and nanotechnology because of the manypossibilities envisaged by the bottom-up approach sincethey possess unique optical, electrical, bonding andcatalytic properties. Among them, the gold clusters arethe most stable and extensively studied materials, andhave been proposed for applications such as in photo-electrochemical devices, drug delivery systems andchemical and immunosensors. In all these cases, theproperties of the materials should be adjusted byanchoring molecular species with suitable properties onthe surface. In this sense, the availability of easily func-tionalizable and stable starting materials is an importantaspect since there is a myriad of molecular species andother materials that can be combined with for the devel-opment of new inorganic-organic hybrid nanomaterialsand applications.


The higher stability and possibility to isolate a solidthat can be repeatedly isolated and redissolved incommon organic solvents without decomposition andthe possibility to treat them just as another organicmolecular species is very convenient. However, there isa drawback for the widespread use of such a thiol pro-tected materials: the sluggishness of the functionaliza-tion reaction by substitution of the protecting species,which can take more than a day to proceed until com-pletion. The use of conventional organic chemistry onω-functionalized protecting molecules is also tediousand hampers the preparation of organic-inorganic hybridnanomaterials, for example by coordinative layer-by-layer assembly. Accordingly, we revisited the Brust-Schiffrin method envisaging the preparation of substi-tutionally reactive but stable enough thiol protected goldnanoparticles to isolate them as a solid.


IX-B-1 Organic Thin-Film Transistors with HighElectron Mobility Based on Perfluoropentacene

INOUE, Youji1; SAKAMOTO, Youichi; SUZUKI,Toshiyasu; KOBAYASHI, Masafumi2; GAO, Yuan2;TOKITO, Shizuo1

(1NHK Sci. Tech. Res. Labs.; 2Kanto Denka Kogyo)

[Jpn. J. Appl. Phys., Part 1 44, 3663–3668 (2005)]

We report on n-channel organic thin-film transistors(OTFTs) based on the novel n-type organic semi-conductor, perfluoropentacene. The transistor exhibitsexcellent electrical characteristics, with a high electronmobility of 0.22 cm2/(V s) and a good current on/offratio of 105. The electron mobility is comparable to thehole mobility of a pentacene OTFT. By combining then-type perfluoropentacene and the p-type pentacene, wehave fabricated ambipolar OTFTs and complementaryinverter circuits. The OTFTs with heterostructures ofthe p- and n-type organic semiconductors can operate asan ambipolar device with high electron and hole mobil-ities of 0.042 and 0.041 cm2/(V s). The complementaryinverter using an n-channel perfluoropentacene OTFTand a p-channel pentacene OTFT exhibits excellenttransfer characteristics with a voltage gain of 45. Acomplementary inverter using the ambipolar OTFTs isalso demonstrated.

IX-B-2 Organic Light-Emitting Diodes UsingMultifunctional Phosphorescent with Iridium-Complex Core and Charge-TransportingDendrons

TSUZUKI, Toshimitsu1; SHIRASAWA, Nobuhiko;SUZUKI, Toshiyasu; TOKITO, Shizuo1

(1NHK Sci. Tech. Res. Labs.)

[Jpn. J. Appl. Phys., Part 1 44, 4151–4154 (2005)]

We report a novel class of light-emitting materialsfor use in organic light-emitting diodes (OLEDs): multi-functional phosphorescent dendrimers that have a phos-phorescent core and dendrons based on charge-trans-porting building blocks. We synthesized first-generationand second-generation dendrimers consisting of a fac-tris(2-phenylpyridine)iridium [Ir(ppy)3] core and hole-transporting phenylcarbazole-based dendrons. Smoothamorphous films of these dendrimers were formed byspin-coating them from solutions. The OLEDs using the

dendrimer exhibited bright green or yellowish-greenemission from the Ir(ppy)3 core. The OLEDs using thefilm containing a mixture of the dendrimer and an elec-tron-transporting material exhibited higher efficiencythan those using the neat dendrimer film. The externalquantum efficiency of OLEDs using the film containinga mixture of the first-generation dendrimer and an elec-tron-transporting material was as high as 7.6%.

Figure 1. Structures of iridium complexes.


IX-B Development of Organic Semiconductors for MolecularThin-Film Devices

Organic light-emitting diodes (OLEDs) and organic field-effect transistors (OFETs) based on π-conjugatedoligomers have been extensively studied as molecular thin-film devices. Organic semiconductors with low injectionbarriers and high mobilities are required for highly efficient OLEDs and OFETs. Radical cations or anions of anorganic semiconductor have to be generated easily at the interface with an electrode (or a dielectric), and holes orelectrons must move fast in the semiconducting layer. Compared with organic p-type semiconductors, organic n-type semiconductors for practical use are few and rather difficult to develop. Recently, we found that perfluorinatedaromatic compounds are efficient n-type semiconductors for OLEDs and OFETs.

IX-C-1 Preparation of Organic Light-EmittingField-Effect Transistors with AsymmetricElectrodes

SAKANOUE, Tomo1; FUJIWARA, Eiichi;YAMADA, Ryo; TADA, Hirokazu(1SOKENDAI)

[Chem. Lett. 34, 494–495 (2005)]

Light-emitting field-effect transistors (LEFET)based on poly [2-methoxy-5-(2-ethylhexoxy)-1,4-phen-ylenevinylene](MEH-PPV) were prepared with asym-metric electrodes of a Au/Cr source and an Al drain on aSiO2 gate insulator (600 nm) through twice of photo-lithography and lift-off techniques (see Figure 1). Thelight emission was observed when the gate voltagesincreased above –40 V at the drain voltage of –100 V.The luminous efficiency of the devices was significantlyimproved comparing to those with conventional elec-trodes of Au/Cr.

Figure 1. Schematic views of the LEFET with asymmetricAu/Cr–Al electordes. (a) Side view of the device. (b) Topview of the FET substrate.

IX-C-2 Field-Effect Transistors Based onSingle-Crystalline Wires of Bis-(1, 2, 5-Thiadiazolo)-p-Quinobis(1, 3-Dithiole)

FUJIWARA, Eiichi; TAKADA, Masaki1;YAMASHITA, Yoshiro2; TADA, Hirokazu(1SOKENDAI; 2Tokyo Inst. Tech.)

[Jpn. J. Appl. Phys. 44, L82–L84 (2005)]

We prepared single-crystalline wires of bis(1, 2, 5-thiadiazolo)-p-quinobis(1, 3-dithiole), whose ends wereanchored to the drain and source electrodes of bottom-contact-type field-effect transistors. Figure 1 shows thetemperature dependence of carrier mobility in the rangefrom 5 K to 330 K. The tunnel transport was found to bedominant at T < 30 K. Thermally activated hoppingbehavior was observed in the temperature range from 30K to 200 K. The mobility decreased with increasingtemperature at T > 200 K, indicating that phonon scat-tering governs carrier transport in single-crystallinewires.

Figure 1. (a) Temperature dependences of the field-effectmobilities of densely packed grains (I) and crystalline wires(II). Each curve is normalized by the mobility at 300 K.Dashed line shows the T–x fitting curve for x = 3. Inset showsArrenius’s plot of curve (I). (b)Temperature dependence of thedrain current of BTQBT wires. The drain and gatevoltageswere –50 V and –30 V, respectively.


IX-C Field-Effect Transistors with Organic Semiconductors

Considerable attention has recently focused on organic field-effect transistors (OFET) because of their potentialuse in low-cost flexible electronic devices. We have studied output characteristics of OFET devices based on newlysynthesized organic compounds with novel device structures.

IX-D-1 Characterization of MolecularAssemblies on Silicon Surfaces by AttenuatedTotal Reflectance Infrared Spectroscopy

ARA, Masato1; YAMADA, Ryo; TADA, Hirokazu(1SOKENDAI)

[Thin Solid Films in press]

Alkyl monolayers anchored to Si(111) were pre-pared in diluted and neat 1-alkene by thermal reaction.Monolayers prepared were investigated by attenuatedtotal reflectance infrared spectroscopy. It was found thatalkyl chains in the monolayers anchored to Si(111) hadan all-trans conformation. The rate of reaction between1-alkene and hydrogen-terminated silicon remarkablydepended on the concentration of 1-alkene as shown inFigure 1. However, monolayers prepared in diluted 1-

alkene were identical with that prepared in neat 1-alkene.

Figure 1. ATR spectra of C12 monolayers prepared in neat 1-dodecene (a) and those prepared in diluted 1-dodecene (b)with a p-polarized configuration, respectively. Reaction wascarried out for 10 s, 30 s, 10 min, 30 min, and 2 h.


IX-E Low Temperature Scanning Tunneling Microscopy andSpectroscopy of Organic Molecules on Metal Surfaces

The electronic structure of molecules adsorbed by metal surfaces is of growing interest in the field not only ofsurface science but also of molecular-scale electronic devices. Scanning tunneling microscopy and spectroscopy areuseful to investigate molecular arrangements and electronic structure with atomic resolution. We have preparedepitaxial films of phathalocyanine molecules on clean metal surfaces and studies there structures by scanningtunneling microscopy and spectroscopy at low temperature.

IX-E-1 Scanning Tunneling Microscopy andSpectroscopy of Phthalocyanine Molecules onMetal Surfaces

TAKADA, Masaki1; TADA, Hirokazu(1SOKENDAI)

[Jpn. J. Appl. Phys. 44, 5332–5335 (2005)]

We studied the electronic structure of cobalt-phthalocyanine (CoPc) molecules on Au(111) and Cu(100) surfaces by scanning tunneling microscopy and

spectroscopy at 5 K. In the differential conductance (dI/dV) spectra as shown in Figure 1, there were somepeaks related to the highest occupied molecular orbital(HOMO), the lowest unoccupied MO (LUMO) and thed-orbitals of the Co atom. CoPc molecules on the Cu(100) surface had new electronic states between thepeaks related to HOMO and LUMO, while those on theAu(111) surface did not show additional peaks. A dI/dVimage indicated that the new states were generated bythe hybridization between the LUMO of molecules andthe electronic states of the Cu(100) surface.

(a) (b)

IX-D Molecular Assemblies on Silicon Surfaces viaSilicon–Carbon Covalent Bonds

Preparation of molecular assemblies on inorganic semiconductors such as silicon and germanium has received agrowing interest because of their potential application to stable regist for nano-patterning. We have prepared organicmonolayers on silicon by wet process and studied film structures with IR.

Figure 1. (a) dI/dV spectra of a single CoPc molecule onAu(111) surface at 5 K. (b) dI/dV spectra of a single CoPcmolecule on Cu(100) surface at 5 K. Spectra (1)–(4) weremeasured at indicated spots on the inset images.


IX-F Ratchet Motions of a Droplet Caused byElectrochemical Reaction of Monolayers

Control of droplet motions on small spaces is of growing interest since it leads to non-mechanical pumpingsystems in micro-fluidic devices. By introducing asymmetric characteristics to the surface, the droplet movesbecause of the imbalance of surface tensions. We found that electrochemical reactions of monolayers were used todynamically control the surface property and the motion of the droplet.

IX-F-1 Electrochemically Generated WettingGradient and Its Application for the Transportof Droplets

YAMADA, Ryo; TADA, Hirokazu

[Langmuir 21, 4254–4256 (2005)]

The reversible transportation of droplets was real-ized by spatiotemporal control of the wetting gradient.The surface wetting was reversibly regulated by usingelectrochemical reactions of the ferrocenyl (Fc) alkane-thiol monolayer and application of the in-plane biasvoltage to the substrate as shown in Figure 1. The back-and-forth motion of the wetting boundary, where thesurface changed from wetting to repulsive, sequentiallycaused a droplet unidirectional spreading and shrinkingon the surface. These unidirectional motions resulted inthe net transport of the droplet in inchworm-like manneras shown in Figure 2. The droplet moved backwardwhen the direction of the in-plane bias voltage wasreversed.

Figure 1. Photographs of nitrobenzene droplets. Vbias wasfixed at 0.35 V and Eoffset was shifted (a–d). Line in thephotograph represents the position of the wetting boundaryestimated from the shape of the droplets. Note that the currentpeak for Fc+/Fc reaction was observed at ca. –0.5 V in cyclicvoltammogram.

Figure 2. Photographs of inchworm motion of the droplet inthe solution. EBIAS = 0.5 V. Eoffset = –300 mV (a), –340 mV(b) and –300 mV (c). (d) Trace of the multi-step inchwormmotions of the droplet. Six photographs were superimposed.

IX-F-2 Transport of a Droplet by DirectionalDeformations with Asymmetric Electrode

YAMADA, Ryo; TADA, Hirokazu

Ratchet motions of a droplet were realized by therepeated deformations of it on an asymmetric V-shapedelectrode. The surface wetting of the electrode wasreversibly regulated by electrochemical reactions of theferrocenyl-alkanehiol monolayer. When the surface waschanged from repulsive to wetting, the contact line ofthe droplet facing to the wider side advanced while theother side was almost pinned. The contact line facing tothe narrower side retracted when the surface waschanged from wetting to repulsive. The directional de-formations of the droplet resulted in a net transport of it.

Figure 1. Directional deformations of the nitrobenzene drop-let. The length of the scale bar in (a) is 3 mm. When the sur-face was changed from repulsive to wetting (a–b), the left sideof the droplet (A) spread. When the surface was back to repul-sive (bc), the right side of the droplet (B) shrank. These direc-tional deformations resulted in a net transport of the droplet.


IX-G-1 Step-Wised Synthesis of MultifunctionalMolecular Wires for Planar Metal-Molecule-Metal Junctions

TANAKA, Shoji

A series of 1–10 nm long building blocks (1-4) havebeen prepared. We have already developed i) “insulatedmolecular modules,” ii) “energy-gap tuning modules,”iii) “molecule-anchor modules,” and iv) “molecularjunction modules” as the basic elements for multi-function integrated π-conjugated macromolecules. Thebuilding blocks 1-4 are widely applicable to assemblethese functional modules in a single molecule. For ex-ample, a series of linear macromolecules (5–6), specifi-cally designed for the systematic investigation of elec-tron conduction in molecular wires, have been preparedeasily from these blocks and modules in a few steps.

Figure 1. Molecular structure of 1–10 nm long buildingblocks. Figure 2. Molecular structure of insulated molecular wires

with anchor units.


S

DodS

S

Dod

NNSi SiSi Si

YX

n=1-8

1: X = Br, Y = Br

( l = 1~10 nm )

2: X = Br, Y = H

3: X = SnBu3, Y = SnBu3

4: X = SnBu3, Y = H

3-60T

Molecular wires for alligator-clip junction ( l = 1~25 nm )

S

DodS

S

Dod

S CNBr

m = 1-2

S

DodS

S

Dod

NNSi SiSi Si

SnBu3Br

n=1-8

+

S

DodS

S

Dod

NNSi SiSi Si 9-36T

S

DodS

S

Dod

S CNS

DodS

S

Dod

SNC

m mn

S

DodS

S

Dod

NNSi SiSi Si

S CNBr

m = 0-6

S

DodS

S

Dod

NNSi SiSi Si

SnBu3Bu3Sn

n=1-8

+

S

DodS

S

Dod

NNSi SiSi Si

S CNSNC

2m+n

Molecular wires for face-to-face junction ( l = 3~15 nm )

5

6

IX-G Development of Multi-Function IntegratedMacromolecules and Their Organization on Substrate

Surfaces for Planar Molecular-Scale Electronics Circuits

The concept of molecular-scale electronics is now realized for individual components such as wire, diode,switch, and memory cell, but the fabrication of complete molecular-scale circuits remains challenging because of thedifficulty of connecting molecular modules to one another. Molecular monolithic technology, which integrates thewiring, transistors and the required passive elements on a single macromolecule, has been proposed as a promisingsolution to this problem. In this project we have been trying to establish both the architecture of this novel class ofmacromolecules and the protocols for their purposive organization on metal/semiconductor substrate surfaces.

IX-H-1 PS-PEG Resin-Supported Palladium-MOP Complexes. Application in Asymmetric π-Allylic Reduction

UOZUMI, Yasuhiro; HOCKE, Heiko

[Tetrahedron 60, 9297–9306 (2004)]

Homochiral palladium complexes of polymeric 2’-,6-, and 6’-anchored 2-diphenylphosphino-1,1’-bi-naphthyl (MOP) ligands were prepared on polystyrene-poly(ethylene glycol) (PS-PEG) resin. The PS-PEGresin-supported palladium-MOP complexes exhibitedhigh catalytic activity, stereoselectivity (up to 80% ee),and recyclability (6 times) in the asymmetric allylicreduction of 1-vinyl-1,2,3,4-tetrahydronaphth-1-yl ben-zoate to give 1-vinyl-1,2,3,4-tetrahydronaphthalene.

IX-H-2 Hydrogenation and Dehalogenationunder Aqueous Conditions with an AmphiphilicPolymer-Supported Nanopalladium Catalyst

NAKAO, Ryu; RHEE, Hakjune; UOZUMI,Yasuhiro

[Org. Lett. 7, 163–165 (2005)]

An amphiphilic polystyrene-poly(ethylene glycol)resin-supported nanopalladium particle catalyzed hydro-genation of olefins and hydrodechlorination of chloro-arenes under aqueous conditions.

IX-H-3 Cycloisomerization of 1,6-Enynes:Asymmetric Multi-Step Preparation of aHydrindane Framework in Water with PolymericCatalysts

NAKAI, Yasushi; UOZUMI, Yasuhiro

[Org. Lett. 7, 291–293 (2005)]

Cycloisomerization of 1,6-enynes proceededsmoothly in water under heterogeneous conditions inthe presence of a palladium complex supported onpolystyrene-poly(ethylene glycol) copolymer resin togive the corresponding cyclopentanes with high level ofchemical greenness. Multi-step asymmetric synthesis ofa hydrindane framework was achieved via palladium-catalyzed asymmetric π-allylic alkylation, propargyla-tion, and cycloisomerization of 1,6-enynes, where allthree steps were performed in water with recyclablepolymeric catalysts.

IX-H-4 Controlled Monoarylation ofDibromoarenes in Water with a PolymericPalladium Catalyst

UOZUMI, Yasuhiro; KIKUCHI, Makoto

[Synlett 1775–1778 (2005)]

A highly selective monoarylation of dibromoareneswas performed via the Suzuki-Miyaura cross-couplingwith arylboronic acids with an amphiphilic polystyrene-poly(ethylene glycol) (PS-PEG) resin-supported phos-phine-palladium complex in water under heterogeneousconditions to give bromobiaryls in high yields. Introduc-tion of two different aryl groups on a aromatic moietywas achieved in a one-pot reaction by successive addi-tion of two kinds of arylboronic acids under similarconditions. The polymeric palladium catalyst can bereadily recovered and recycled.


IX-H Heterogeneous Aquacatalysis

Catalytic organic transformations under mild, safe, and green conditions is an important goal in synthetic organicchemistry. We recently reported that several palladium- and rhodium-catalyzed reactions, including π-allylicsubstitution, carbonylation, the Heck reaction, Suzuki-Miyaura cross-coupling, hydroformylation, cyclotrimerizationof alkynes, and Michael-type addition of arylboronic acids, etc., took place in water by use of metal-phosphinecomplexes anchored on to an amphiphilic polystyrene-poly(ethylene glycol) graft copolymer (PS-PEG) resin wherethe advantages of both aqueous- and heterogeneous-switching of a given catalytic transformation were combined inone system. Here we wish to report our progress in this subject.

IX-I-1 Gold Nanoparticles Stabilized by TripodThioether Oligomers: Synthesis and MolecularDynamics Studies

HOSOKAWA, Youichi; MAKI, Suguru; NAGATA,Toshi

[Bull. Chem. Soc. Jpn. in press (2005)]

Gold nanoparticles (1.5–1.7 nm) were prepared byuse of three tripod thioether oligomers (TTOs) asstabilizing molecules shown in Figure 1. The ICP-AESanalyses of these TTO/Aun composites revealed thenumber of protecting molecules per nanoparticles as25±19, 23±21, and 10±6. On the other hand, themolecular models suggested that the TTOs were ofcomparable sizes with the sizes of nanoparticles. Inorder to account for this discrepancy, we carried outmolecular dynamic simulations of the TTO/Aun com-posites. The interaction parameters between organicmolecules and the gold surface were newly developedso that they reproduced the adsorption enthalpies ofsmall sulfur-containing molecules on the Au(111) sur-face. By use of these parameters, the self-assemblyprocess of TTO molecules on the Au147 surface wassimulated in chloroform solvent. Figure 2 shows thetypical results from a single run, in which 16 TTO mol-ecules (1a) and an Au147 nanoparticle (a cuboctahedralstructure; diameter 1.7 nm) were placed in a box ofCHCl3 with dimensions 112.2×96.3×97.7 Å3. Thesurface of the gold nanoparticle was completely coveredwith three TTO molecules. Although it is not impossibleto accommodate more than 20 1a’s around the surfaceof a gold nanoparticle, the more appropriate modelwould be coexistence of free, unbound 1a moleculesand gold nanoparticles covered with a small number of1a. The free and bound 1a molecules should be indynamic equilibrium in CHCl3 solutions, as suggested

by the 1H NMR spectra which showed only one set ofslightly broadened signals.

Figure 1. The tripod thioether oligomers used in this study.

Figure 2. A snapshot structure from the 1a16/Au147 simula-tion, in which three 1a molecules are adsorbed on the Au147

surface. The space-filling views from two opposite directionsare shown. The gold nanoparticle and the three different 1amolecules are denoted in white color and three different levelsof gray colors, respectively.


IX-I Development of New Nanomaterials as Components inAdvanced Molecular Systems

Nanometer-sized materials exhibit unique electronic behavior. In the quest of advanced redox catalysis, we arecurrently interested in combining nanometer-sized materials into molecular redox systems. As a basic architecture,composites of organic molecules and gold nanoparticles were synthesized and molecular dynamic simulations werecarried out to predict the solution structures.

IX-J Designing Artificial Photosynthesis at MolecularDimensions

Photosynthesis is one of the finest piece of molecular machinery that Nature has ever created. Its ultrafastelectron transfer and following well-organized sequence of chemical transformation have been, and will continue tobe, challenging goals for molecular scientists. Our ultimate goal is to design artificial molecular systems that effectmultiple chemical reactions triggered by light on the basis of molecular rationale.

IX-J-1 Electrochemical Properties ofFerrocene-Dendrimer-Porphyrins

KIKUZAWA, Yoshihiro; NAGATA, Toshi

Synthesis of the ferrocene-dendrimer-porphyrins(Figure 1) was already reported in previous AnnualReviews. Figure 2 shows the differential pulse voltam-mograms (DPV) of Gn(Fc)m-ZnP, together with thereference compounds Bn-ZnP and Fc-ZnP, in CH2Cl2/0.1 mol/dm3 Bu4NClO4. The ferrocene-dendrimer-por-phyrin compounds showed three oxidation peaks at 0.2,0.5 and 0.7 V (vs FeCp2/FeCp2

+), which were assignedas the oxidation of the ferrocenyl groups, and the firstand second oxidation of the porphyrin. Figure 3 showsthe plots of imax (the peak height) versus ∆t–1/2 (∆t is thepulse width) for the first two oxidation peaks of G3(Fc)14-ZnP. The values for peak II showed good lin-earity, whereas those for peak I showed pronounceddeviation from linearity. These results indicate that theelectron transfer for the first oxidation (peak I) is slowin the electrochemical timescale. This slow kinetics canbe attributed to the reorganization of the supportingelectrolyte during the multiple electron transfer of theferrocene-dendrimer redox pool.

Figure 1. The structure of the ferrocene-dendrimer-linkedporphyrins.

Figure 2. The differential pulse voltammograms of theferrocene-dendrimer-porphyrins.

Figure 3. The imax-∆t–1/2 plots of the first two oxidation peaksof G3(Fc)14-ZnP.


O

O

O OOO OOO

Fe

OO

Fe

OO

Fe

OO

N NNN

FF

F F F

F

Zn

O

O

O OOO O

Fe

OO

Fe

OO

N NNN

FF

F F F

F

Zn

O

O

O OO

Fe

OO

N NNN

FF

F F F

F

Zn

2 2 2

2 2

2

G3(Fc)14-ZnP

G2(Fc)6-ZnP

G1(Fc)2-ZnP

O

Fe

ON N

NNFF

F F F

F

Zn O N NNN

FF

F F F

F

Zn

1 µA

G3(Fc)14-ZnP

G2(Fc)6-ZnP

G1(Fc)2-ZnP

Fc-ZnP

Bn-ZnP

I

II

∆t –1/2 sec–1/2

i max

(µA

)

IX-K Development of New Metal Complexes as RedoxCatalysts

Redox catalysis is an important field of chemistry which translates a flow of electron into chemicaltransformation. It is also one of the requisites for artificial photosynthesis. This project of ours aims at developingnew metal complexes that perform redox catalysis at low overpotential. Currently we are focusing our attention tothe development of a series of cobalt phosphine complexes as possible catalysts for electrochemical reductions.

IX-K-1 Synthesis, Structure andElectrochemistry of New Cobalt Complexeswith Cyclopentadienyl and Bidentate Ligands

NAGASAWA, Takayuki; NAGATA, Toshi

Low-valent cobalt complexes are interesting candi-dates for electrocatalytic reductions. Herein we reportthe synthesis, structure, and electrochemistry a series ofcobalt complexes with general formula [Cp*Co(L)(S)]2+, where Cp* is pentamethylcyclopentadienylanion, L is a bidentate ligand and S is an exchangablemonodentate ligand.

The key intermediate compound, [Cp*Co(SMe2)3](BF4)2, was prepared from Cp*Co(CO)2 by a similarmethod as the Cp analog reported by Kuhn. The reac-tion of this compound with a bidentate ligand in CH3NO2, followed by treatment with CH3CN/Et2O, gave acrystalline product [Cp*Co(L)(CH3CN)](BF4) in 80–90% yield (Scheme 1). The X-ray structure of 2 (L =dppp) is shown in Figure 1, which shows typical octa-hedral coordination of the Co(III) center. The cyclicvoltammograms in CH3CN showed two reversiblewaves corresponding to the Co(III)/Co(II) and Co(II)/Co(I) redox couples (Table 1).

Scheme 1. Synthesis of the cobalt complexes.

Figure 1. The ORTEP drawings of (a) the cationic part, and(b) the asymmetric unit of 2.

Table 1. The reversible half-wave potentials of 1-4 inCH3CN/Bu4NClO4.


1. MeNO2, r.t.2. CH3CN/Et2O

[(Cp*Co(L)(CH3CN)](BF4)2

[Cp*Co(SMe2)3](BF4)2 + L

L = Ph2P(CH2)2PPh2 (1)

Ph2P(CH2)3PPh2 (2)2,2'-bipyridyl (3)

H2N(CH2)2NH2 (4)

E1/2(V vs. Cp2Fe/Cp2Fe+)Co(III)/Co(II) Co(II)/Co(I)

-0.61

-0.56

-0.98

-0.82

1

2

4

3

-1.13

-1.26

-2.25

-1.15

(a)

(b)

IX-L-1 Photochemistry of Cyclohexane onCu(111)

YAMAGUCHI, Dai; MATSUMOTO, Taketoshi;WATANABE, Kazuya; TAKAGI, Noriaki1;MATSUMOTO, Yoshiyasu(1SOKENDAI and Univ. Tokyo)

[Phys. Chem. Chem. Phys. submitted]

The photochemistry of cyclohexane on Cu(111) andits excitation mechanism have been studied by tempera-ture-programmed desorption, ultraviolet and X-rayphotoelectron spectroscopy. Cyclohexane weakly ad-sorbed on Cu(111) has been known to show a broad-ened and redshifted CH stretching band, i.e., CH vibra-tional mode softening. Although no dehydrogenationtakes place thermally on this surface and by the irradia-

tion of photons at 5.0 eV, adsorbed cyclohexane is dis-sociated to cyclohexyl and hydrogen by the irradiationof photons at 6.4 eV. This is a marked contrast to cyclo-hexane in the gas phase where the onset of absorption islocated at 7 eV. When the surface irradiated by 6.4-eVphotons is further annealed, cyclohexyl is dehydro-genated to form cylcohexene that desorbs at 230 K. Thesystematic measurements of photochemical cross sec-tions at 6.4 eV with linearly polarized light as a functionof incident angle indicate that the electronic transitionfrom the highest occupied band of cyclohexane to apartially occupied hybridized band near the Fermi levelis responsible for the photochemistry. The hybridizedband is formed by the interactions between the electron-ic states of cyclohexane and the metal substrate. Therole of the hybridized band in the photochemistry andthe CH vibrational mode softening is discussed.


IX-L Photochemistry on Well-Defined Surfaces

Upon the irradiation of light in the wavelength range from visible to ultraviolet, a number of adsorbed moleculeson metal surfaces reveal variety of photochemical processes, including photo-stimulated desorption, rearrangementof adsorbed states, photodissociation, and photo-initiated reactions with coadsorbates. A central and fundamentalquestion in the surface photochemistry is to clarify how adsorbate-substrate systems are excited by photonirradiation. In addition, since photo-initiated reactions can be induced without any thermal activation of reactants,they may provide good opportunities for studying a new class of surface reactions that may not be inducedthermally. We have studied photochemistry of various adsorption systems on well-defined metal and semiconductorsurfaces mainly by temperature-programmed desorption (TPD), infrared reflection absorption spectroscopy (IRAS),x-ray photoelectron spectroscopy (XPS), work function measurements, and angular-resolved time-of-flight (TOF)mass spectrometry of photodesorbed species associated with pulsed laser irradiation. In this year, the photo-chemistry of cyclic alkane on Pt(111) and Cu(111) surfaces was studied mainly by TPD, XPS, and IRAS.

IX-M Ultrafast Dynamics at Well-Defined Surfaces

To understand the mechanism of surface photochemistry, it is vital to know how photoinduced electronicexcitation induces adsorbate nuclear motions that ultimately lead to chemical reactions. We demonstrate the real-time observations of surface phonons and adsorbate-substrate vibrational modes by fs time-resolved secondharmonics generation (TRSHG). If an excitation light pulse has a duration sufficiently shorter than a period of avibrational mode or a phonon mode, it can excite the mode with a high degree of temporal and spatial coherence.This coherent nuclear motion modulates the second-order susceptibility χ(2). Thus, by monitoring the intensitymodulation of the second harmonics (SH) generation of a probe pulse, we can observe the evolution of the coherentnuclear motion subsequent to the electronic excitation at the surfaces. This year, in particular, we have demonstratedthat coherent phonon modes can be selectively excited by tailored pulse trains.

IX-M-1 Femtosecond Wavepacket Dynamics ofCs Adsorbates on Pt(111): Coverage andTemperature Dependences

WATANABE, Kazuya; TAKAGI, Noriaki1;MATSUMOTO, Yoshiyasu(1Univ. Tokyo)

[Phys. Rev. B 71, 085414 (9 pages) (2005)]

Femtosecond time-resolved second harmonic gen-eration has been used to observe vibrational wavepacket

dynamics at a Cs-covered Pt(111)surface. The creationand dephasing of vibrational coherence are monitoredvia the intensity modulations in the second harmonic ofprobe pulses as a function of pump-probe delay. TheTRSHG trace obtained from the clean surface shows aninstantaneous sharp rise right after the excitation. This isfollowed by a fast decaying component (t < 1 ps) and aslowly decaying one persistent to the longest delay (t =6 ps) of the measurements. When the surface is coveredwith Cs, SH signals are enhanced by about 70 times andstrongly modulated waveforms are superimposed on theTRSHG traces. The oscillatory signals are found in

TRSHG signals upon the excitations at 580 and 800 nm,which are the manifestation of nuclear wavepacketdynamics on the surface. The Cs-coverage dependencestudied in detail indicates that the wavepacket dynamicsof Cs–Pt stretching modes and Pt surface phonon modesare responsible for the TRSHG signals. The cos-likeinitial phase of the oscillatory signals and the coveragedependence of the initial amplitude suggest that thevibrational coherence is associated with the resonantexcitation between Cs-derived states in the quantumwell of the Cs overlayer. The rate of Cs–Pt vibrationaldephasing increases with the surface temperature. Thisbehavior cannot be accounted for by the increasingcontribution from hot bands of low frequency modes.Instead, pure dephasing caused by anharmonic couplingbetween Cs–Pt stretching and parallel modes in the Csoverlayer is likely the dominant mechanism for thevibrational dephasing.

IX-M-2 Mode Selective Excitation of CoherentSurface Phonons on Alkali-Covered MetalSurfaces

WATANABE, Kazuya; TAKAGI, Noriaki1;MATSUMOTO, Yoshiyasu(1Univ. Tokyo)

[Phys. Chem. Chem. Phys. 7, 2697–2700 (2005)]

We demonstrate the mode selective excitation ofcoherent phonons at Pt(111) surfaces covered withsubmonolayer cesium atoms. A burst of 150-fs laser

pulses with the repetition rate of 2.0 ~ 2.9 THz wassynthesized by using a spatial-light modulator, and usedfor the coherent surface phonon excitation. The coherentnuclear motion was monitored by time-resolved secondharmonic generation. By tuning the repetition rate, wesucceeded in controlling the relative amplitude of thevibrational coherence of the Cs–Pt stretching mode (2.3~ 2.4 THz) to that of the Pt surface Rayleigh phononmode (2.6 or 2.9 THz, depending on the Cs coverage).

IX-M-3 Excitation Mechanism of CoherentSurface Phonons on Alkali-Metal CoveredSurfaces

FUYUKI, Masanori1; WATANABE, Kazuya;MATSUMOTO, Taketoshi; MATSUMOTO,Yoshiyasu(1SOKENDAI)

We observed time-resolved second harmonic signalsfrom the Cu(111) surface with a full monolayer of Na inultra-high vacuum and investigated the excitation-wave-length dependence of the wave packet dynamics of thecoherently excited Na–Cu stretching mode. Changingthe photon energy of the pump pulse (25 fs) from 2.0 to2.5 eV, the oscillation amplitude derived from the Na–Cu stretching motion is enhanced when the photonenergy is resonant to the transitions from the groundstate to image states. Thus, these measurements clearlyindicate that the resonant excitation of electronic state ofthe adsorbate is essential for creation of the coherentsurface phonons.


IX-N Multiphoton Photoelectron Spectroscopy of ElectronicStates of Nano-Structured Materials on Surfaces

Electronic structure and excited state dynamics of nano-structured materials on surfaces are very important forexploring their properties, thermal reactivity and nonthermal processes including photochemistry and photo-inducedcharge transfer. For this purpose, we performed multiphoton photoelectron spectroscopy with the fs time resolution.In this year we applied this method to thin films of tris-(8-hydroxyquinoline) aluminum (Alq3).

IX-N-1 The Electronic Structure andFemtosecond Electron Transfer Dynamics atNoble Metal/tris-(8-hydroxyquinoline)Aluminum Interfaces

INO, Daisuke1; WATANABE, Kazuya; TAKAGI,Noriaki2; MATSUMOTO, Yoshiyasu(1SOKENDAI; 2Univ. Tokyo)

[Phys. Rev. B 71, 115427 (10 pages) (2005)]

The electronic structures of tris-(8-hydroxyquino-line) aluminum (Alq3) on Cu(111) and Au(111) surfacesare studied by using ultraviolet photoelectron spectros-copy and two-photon photoelectron (2PPE) spectros-

copy. The work function decreases with increase of thecoverage due to surface dipole of 5.1 D along the sur-face normal. The ionization potential from the highestoccupied state 6.38 eV does not depend on the metalsubstrates used in this study. The anion states of Alq3adsorbed is created by photoinduced electron transferfrom the metal substrates and are located at 2.85 and3.71 eV above the Fermi level on Cu(111) and Au(111)surfaces, respectively. The full width at half maximumof the anion states is 0.2 eV on both the surfaces. Time-resolved 2PPE measurements show that the anion statecreated by electron transfer from the metal decays withthe lifetime of 31±2 fs on Cu(111) and about three timesshorter on Au(111). The angle-resolved 2PPE and thecoverage dependence of the lifetime of the anion state

indicate that the electron transferred from the metalsurface is localized at a molecule in the first layer. Thus,the ultrafast electron back transfer from the anion state

of Alq3 in the first layer dominates over the electronhopping to the second layer.


IX-O Chemistry of One-Dimensional Nano-SurfaceCompounds Studied by Scanning Tunneling Microscopy

The fluctuating configurations of low-dimensional structures can be thermodynamically favorable at finitetemperatures, because the energy gain overcomes the energy cost that accompanies local structural fluctuation. Inparticular, one-dimensional (1D) systems have a propensity to be sensitive to these fluctuations as described by oneof the maxims of condensed matter physics, i.e., one chain does not make a crystal. Thus, the dynamical formationof active species and sites by these fluctuations is a key factor in establishing a microscopic model for chemicalreactions at surfaces and nano-structured compounds.

IX-O-1 In-Situ Observation of CO Oxidation onAg(110)(2x1)-O by Scanning TunnelingMicroscopy: Structural Fluctuation andCatalytic Activity

NAKAGOE, Osamu1; WATANABE, Kazuya;TAKAGI, Noriaki2; MATSUMOTO, Yoshiyasu(1SOKENDAI; 2Univ. Tokyo )

[J. Phys. Chem. B 109, 14536–14543 (2005)]

It is well known that the adsorption of O on Ag(110)results in the formation of quasi-1D structures, AgOchains, accompanied by the mass transfer of substrateatoms.

AgO chains arrange periodically to form (n×1) (n =2 ~ 7) depending on the fractional O coverage due torepulsive inter-chain interactions. On the added-rowreconstructed Ag(110)(n×1)–O surfaces where one-dimensional –Ag–O–Ag–O– chains arrange periodical-ly, the clean-off reaction of O adatoms by CO wasinvestigated using variable temperature scanning tun-neling microscopy (VT-STM). Based on the in situSTM observations of the surface structure variation inthe course of the reaction at various temperatures, wefound that the reaction kinetics are significantly affectedby the structural transition of AgO chains from a solidstraight line configuration to dynamically fluctuatingconfigurations. Below 230 K where the chains arestraight, the reaction takes place only at the end of thechains, so that the reaction progresses in the zero-orderkinetics with the reaction front propagating along thechain. The temperature dependence of the reaction ratesyields the activation barrier of 41 kJ/mol and the pre-exponential factor of 1.7 × 103 cm–2 s–1. At room tem-perature, the reaction rate is drastically acceleratedwhen almost half of the O adatoms are eliminated andthe chains start fluctuating. The dynamic formation ofactive sites equivalent to the end of chains upon thechain fluctuation results in the nonlinear increase of thereaction rate.

IX-P-1 Glutathione-Protected Gold ClustersRevisited: Bridging the Gap between Gold(I)-Thiolate Complexes and Thiolate-ProtectedGold Nanocrystals

NEGISHI, Yuichi; NOBUSADA, Katsuyuki;TSUKUDA, Tatsuya

[J. Am. Chem. Soc. 127, 5261–5270 (2005)]

Small gold clusters (~1 nm) protected by moleculesof a tripeptide, glutathione (GSH), were prepared byreductive decomposition of Au(I)-SG polymers at a lowtemperature and separated into a number of fractions bypolyacrylamide gel electrophoresis (PAGE). Chemicalcompositions of the fractionated clusters determinedpreviously by electrospray ionization (ESI) mass spec-trometry1) were reassessed by taking advantage offreshly-prepared samples, higher mass resolution andmore accurate mass calibration; the nine smallest com-ponents are reassigned to Au10(SG)10, Au15(SG)13, Au18(SG)14, Au22(SG)16, Au22(SG)17, Au25(SG)18, Au29(SG)20, Au33(SG)22, and Au39(SG)24. These assign-ments were further confirmed by measuring the massspectra of the isolated Au:S(h-G) clusters, where h-GSHis a homo-glutathione. It is proposed that a series of theisolated Au:SG clusters corresponds to kineticallytrapped intermediates of the growing Au cores. Therelative abundance of the isolated clusters was cor-related well with the thermodynamic stabilities againstunimolecular decomposition. The electronic structuresof the isolated Au:SG clusters were probed by X-rayphotoelectron spectroscopy (XPS) and optical spectros-copy. The Au(4f) XPS spectra illustrate substantialelectron donation from the gold cores to the GS ligandsin the Au:SG clusters. The optical absorption and photo-luminescence spectra indicate that the electronic struc-tures of the Au:SG clusters are well quantized: embryosof the sp band of the bulk gold evolve remarkablydepending on the numbers of the gold atoms and GSligands. The comparison of these spectral data withthose of sodium Au(I) thiomalate and 1.8-nm Au:SGnanocrystals (NCs) reveals that the subnanometer-sizedAu clusters thiolated constitute a distinct class of binarysystem which lies between the Au(I)-thiolate complexesand thiolate-protected Au NCs.

Reference1)Y. Negishi et al., J. Am. Chem. Soc. 126, 6518 (2004).

Figure 1. Chemical compositions of the Au:SG clustersisolated in the present study.

IX-P-2 Large-Scale Synthesis of Thiolated Au25Clusters via Ligand Exchange Reactions ofPhosphine-Stabilized Au11 Clusters

SHICHIBU, Yukatsu1; NEGISHI, Yuichi;TSUKUDA, Tatsuya; TERANISHI, Toshiharu2

(1JAIST; 2Univ. Tsukuba)

[J. Am. Chem. Soc. 127, 13464–13465 (2005)]

Phosphine–stabilized Au11 clusters in chloroformwere reacted with glutathione (GSH) in water under anitrogen atmosphere. The resulting Au:SG clustersexhibit an optical absorption spectrum similar to that ofAu25(SG)18, which was isolated as the major productfrom chemically prepared Au:SG clusters.1) Rigorouscharacterization by optical spectroscopy, electrosprayionization mass spectrometry, and polyacrylamide gelelectrophoresis confirms that the Au25(SG)18 clusterswere selectively obtained on the sub-100-mg scale byligand exchange reaction under aerobic conditions. Theligand exchange strategy offers a practical and conven-ient method of synthesizing thiolated Au25 clusters on alarge scale.

Reference1)Y. Negishi et al., J. Am. Chem. Soc. 127, 5261 (2005).

Figure 1. Large-scale synthesis of the Au25(SG)18 clusters vialigand exchange reactions.


IX-P Structures, Stabilities and Physicochemical Propertiesof Organometallic Hybrid Clusters

Recently, metal clusters have gained much attention because they exhibit novel physicochemical properties thatare beyond the prediction made by a dimensional scaling of those of the corresponding bulk. In this regard, metalclusters protected by thiolates or stabilized by polymers are promising candidates for elementary units of nano-scaledevices. Our interests are focused on the following issues on the organometallic hybrid clusters: (1) a large-scalepreparation of the subnanometer-sized clusters, (2) development of size–selection method, (3) determination ofchemical compositions of size-selected clusters (i.e. the numbers of metal atoms and organic molecules), and (4)elucidation of effect of the core size, core shape, and interaction with organic molecules on stabilities, electronicstructures, and chemical properties.

IX-P-3 Subnanometer-Sized Gold Clusters withDual Molecular Receptors: Synthesis andAssembly in One-Dimensional Arrangements

NEGISHI, Yuichi; TSUNOYAMA, Hironori;YANAGIMOTO, Yasushi1; TSUKUDA, Tatsuya(1Okayama Univ.)

[Chem. Lett. 34, 1638–1639 (2005)]

The gold (Au:S-β-CD) clusters modified by thio-lated β-cyclodextrin (HS-β-CD) were prepared byreduction of AuCl4– with NaBH4 in DMSO solution: theconcentration ratio, [HS-β-CD]/[AuCl4–], was fixed at1. Interestingly, the core size distribution of the Au:S-β-CD clusters determined by TEM measurements exhibitsbimodal core-size distribution centered at ca. 1.1 and2.4 nm. These two components were successfullyseparated by using polyacrylamide gel electrophoresis(PAGE). The low-mobility clusters contain the Au coreswith the average diameter of 2.3±0.4 nm whose opticalabsorption spectrum exhibits the surface plasmon bandpeaked at ca. 520 nm. In contrast, the Au clusters withthe sizes of ~1 nm are barely discernible in the TEMimage of the high-mobility clusters (Au-1). The opticalspectroscopy and the thermogravimetric measurementsuggest that fraction Au-1 is composed of the Au12–15cores protected by two β-CD ligands. Since the diam-eter of the circle made by seven sulfurs of the S-β-CD iscomparable to the Au core size, this result inevitablyimplies that two S-β-CD ligands are attached to the Aucore so that the hydrophobic cavities are pointed towardthe opposite side. This structural hypothesis was con-firmed by the formation of one-dimensional assembliesof Au-1 through binding interaction with ferrocenedimers (see structure in Figure 1). By use of tailor-mademolecules as linkers, the Au-1 clusters may be assem-bled in well-ordered arrangements with desired symme-try and interparticle distance.

Figure 1. One-dimensional arrangements of Au-1 formed byhost-guest interaction with ferrocene diemers.

IX-P-4 Size-Specific Catalytic Activity ofPolymer-Stabilized Gold Nanoclusters forAerobic Alcohol Oxidation in Water

TSUNOYAMA, Hironori; SAKURAI, Hidehiro;NEGISHI, Yuichi; TSUKUDA, Tatsuya1

(1IMS, CREST)

[J. Am. Chem. Soc. 127, 9374–9375 (2005)]

Gold nanoclusters (φ = 1.3 nm) stabilized by poly(N-vinyl-2-pyrrolidone) (Au:PVP NCs) readily oxidizebenzylic alcohols to the corresponding aldehydes and/or

carboxylic acids under ambient temperature in water.Kinetic measurement revealed that smaller Au:PVPNCs exhibit higher catalytic activity than larger (9.5nm) homologues and, more surprisingly, than Pd:PVPNCs of comparable size (1.5 and 2.2 nm). On the basisof the marked difference in the kinetic isotope effectand activation energy between Au:PVP and Pd:PVPNCs, a reaction mechanism for alcohol oxidation cata-lyzed by Au:PVP NCs is proposed in which a superoxo-like molecular oxygen species adsorbed on the surfaceof the small Au NCs abstracts a hydrogen atom from thealkoxide.

Figure 1. Time-course of conversion of p-hydroxyl benzyl-alcohol by Au:PVP NCs (φ = 1.3 and 9.5 nm).

IX-P-5 Fabrication of Two dimensional Arraysof Size-Selected Gold Clusters

TSUNOYAMA, Hironori; NEGISHI, Yuichi;TSUKUDA, Tatsuya1

(1IMS, CREST)

Alkanethiolate-protected gold (Au:SR) clusters ofthe size range of 1 ~ 5 nm were prepared by a ligandexchange of polymer-stabilized gold clusters (Au:PVP)1) dispersed in water and subsequent heat treat-ment.2) The Au:SR clusters thus obtained were sizeselected by using gel permeation chromatography(GPC).3) The mass spectrometric characterization of thefractionated samples has revealed that the magic-num-bered gold clusters with core masses of 8 kDa (1.1 nm),14 kDa (1.3 nm), 22 kDa (1.5 nm), and 28 kDa (1.7nm)4) can be isolated by the GPC in a recycled opera-tion. As for the Au:SR clusters of > 2 nm, the GPCseparation yielded the sized selected clusters with aresolution of one atomic shell (0.5 nm in diameter).Two-dimensional arrays of the size-selected Au:SRclusters were fabricated by Langmuir-Brodgett tech-nique. The structures of the films transferred to theamorphous carbon and other substrates (graphite andtitania) were characterized by TEM, AFM, and SEM.Fabrication of model catalytic systems by using thecluster film thus prepared is now underway in collabo-ration with the groups of Profs. Al-Shamery (OldenburgUniv.) and Matsumoto (IMS).

References1)H. Tsunoyama et al., Langmuir 20, 11293 (2004).2)T. Shimizu et al., J. Phys. Chem. B 107, 2719 (2003).3)H. Murayama et al., J. Phys. Chem. B 108, 3496 (2004).4)T. G. Schaaff et al., J. Phys. Chem. B 101, 7885 (1997).


IX-Q-1 Ultra-High Field NMR Study ofCarbohydrate-Protein Interactions

KAMIYA, Yukiko1; YAMAGUCHI, Yoshiki2;SASAKAWA, Hiroaki1; KATO, Koichi1(1IMS and Nagoya City Univ.; 2Nagoya City Univ.)

NMR analyses of glycans have been hampered byspectral overlap and low sensitivity. It is obviouslyadvantageous to measure NMR spectra of these mol-ecules at an ultra-high magnetic field because of highresolution and high sensitivity. We demonstrate that the920 MHz NMR spectra provide us with atomic informa-tion on complicated glycoconjugates.

The vesicular integral protein of 36 kDa (VIP36) isan intracellular animal lectin, which act as a putativecargo receptor recycling between the Golgi and theendoplasmic reticulum. Although VIP36 has beenreported to recognize glycoproteins carrying highmannose-type oligosaccharides, very little has beenknown about structural aspects of the sugar-bindingmodes of this cargo receptor. We have therefore ana-lyzed the interactions between a recombinant carbo-hydrate recognition domain of VIP36 (VIP36-CRD) andchemically synthesized oligosaccharides by use ofnuclear magnetic resonance spectroscopy.

Figure 1a shows the anomeric regions of the 500MHz 1H NMR spectra of Man9GlcNAc2. The signalsderived from Man-D1, Man-D2 and Man-D3 are severe-ly degenerated. In contrast, these peaks are perfectlyseparated in the 920 MHz NMR spectrum (Figure 1b).

The one-dimensional 1H NMR spectra of Man9GlcNAc2 titrated with VIP36-CRD were observed foridentification of sugar residues involved in binding tothis lectin domain. Upon titration with VIP36-CRD,selective line broadening was observed for the signalsoriginating from the mannose residues at positions 4, C,and D1, which correspond to the D1 arm of the Man9GlcNAc2 (Figure 1c,d). On the basis of these data, weconclude that VIP36-CRD interacts predominantly withthe D1 arm of high-mannose oligosaccharides.

Figure 1. 1H NMR spectra of oligosaccharide, Man9GlcNAc2

(anomeric region). These spectra were recorded at the 1Hfrequency of 500 MHz(a) and 920 MHz(b–d) in the absence(a, b) and presence of 0.2 equiv.(c) and 0.5 equiv.(d) ofVIP36-CRD.

IX-Q-2 Ultra-High Field NMR Study ofGlycoproteins

NAGANO, Mayumi1; YAMAGUCHI, Yoshiki2;SASAKAWA, Hiroaki1; KATO, Koichi1(1IMS and Nagoya City Univ.; 2Nagoya City Univ.)

Many of the proteins in the living systems expresscarbohydrate moieties. Although the biological impor-tance of oligosaccharides covalently linked to proteinshas been widely recognized, little is known about theirspecific roles from the structural aspect. This deficiencyin our knowledge is largely due to the lack of an appro-priate methodology to deal with glycoproteins as targetsof structural biology. The carbohydrate moieties ofglycoproteins generally exhibit microheterogeneitiesand possess a significant degree of freedom in internalmotion, which hampers crystallization or interpretationof electron density. NMR spectroscopy can potentiallyprovide us with information on structure and dynamicsof glycoproteins in solution. However, there are fewreports of structural determination of glycoproteins byNMR spectroscopy. In this situation, we have beendeveloping NMR techniques for structural analyses atatomic resolution of glycoproteins in solution. In thismethodology, the glycans and/or polypeptides of glyco-


IX-Q Structural Analyses of Biological Macromolecules byUltra-High Field NMR Spectroscopy

Our research seeks the underlying molecular basis for the function of biological macromolecules. In particular,we are interested in the function of molecular machines that work in the cellular processes involving protein folding,transport and degradation, and of glycoproteins playing important roles in the humoral and cellular immune systems.By use of ultra-high field NMR spectroscopy, we aim to elucidate the three-dimensional structure, dynamics, andinteractions of proteins and glycoconjugates at the atomic level. A knowledge gained in this project will provide thestructural basis for the rational design of drugs and biomolecular engineering that contribute towards a detailedunderstanding of biological systems.

proteins are uniformly or selectively labeled with stableisotopes (13C, 15N, and 2H) by metabolic or enzymaticmanners. We demonstrate our strategy using the Fcportion of immunoglobulin G (IgG) as a model system.A series of double and triple resonance experimentswere performed for the uniformly 13C/15N-labeled IgG-Fc. Figure 1 shows the 2D HSQC spectrum of IgG-Fcrecorded on a 920 MHz NMR spectrometer. Thesespectra enabled us to assign the signals originating fromthe polypeptide backbone and the carbohydrate moi-eties. The NMR spectral data provide us with the basisfor elucidation of structure and dynamics of the carbo-hydrate moieties as well as the polypeptide chains of theFc glycoprotein in solution.

Figure 1. 1H-13C HSQC spectrum of the carbohydrate moi-eties of isotopically labeled IgG-Fc. The assignments ofanomeric peaks are indicated in the spectrum.


IX-R-1 Development and Use of a Multichannel(e,2e) Spectrometer for Electron MomentumDensities of Molecules

TAKAHASHI, Masahiko1; UDAGAWA, Yasuo1

(1IMS and Tohoku Univ.)

[J. Phys. Chem. Solids 65, 2055–2059 (2004)]

We have developed an (e,2e) spectrometer with theintroduction of modern multiparameter techniques. Inparticular, the high sensitivity achieved by simultaneousdetection in energy and momentum is remarkable,opening up the possibilities of more precise and moreadvanced studies on the electronic structure of atomsand molecules. To illustrate some of the features, anoverview of our recent results is presented. Highlightsare applications to collision dynamics of H2 and devel-opment of a method for a complete three-dimensionalmapping of electron momentum densities in gaseousmolecules. Both of these studies are based on the highsensitivity of the spectrometer.

IX-R-2 Observation of Molecular Frame (e,2e)Cross Section Using an Electron-Electron-Fragment Ion Triple Coincidence Apparatus

TAKAHASHI, Masahiko1; WATANABE, Noboru1;KHAJURIA, Yugal2; NAKAYAMA, Kazuya3;UDAGAWA, Yasuo1; ELAND, John H. D.4(1IMS and Tohoku Univ.; 2IMS and IIT Madras;3Tohoku Univ.; 4IMS and Oxford Univ.)

[J. Electron Spectrosc. Relat. Phenom. 141, 83–93(2004)]

An apparatus for electron-electron-fragment iontriple coincidence experiments has been developed toexamine binary (e,2e) scattering reaction in the molecu-lar frame. In the axial recoil limit of fragmentation ofthe residual ion, measurements of vector correlationsamong the three charged particles are equivalent to(e,2e) experiments with fixed-in-space molecules.Details and performance of the apparatus are reported,together with preliminary result of collision dynamics

study on ionization-excitation processes of fixed-in-space H2 molecules. We believe that this is the firstobservation of molecular frame (e,2e) cross sections.

IX-R-3 (e,3e) Collisions on Mg in the ImpulsiveRegime Studied by Second BornApproximation

WATANABE, Noboru1; COOPER, John W.2; VANBOEYEN, Roger W.3; DOERING, John P.3;MOORE, John H.2; COPLAN, Michael A.2(1IMS and Tohoku Univ.; 2Univ. Maryland; 3JohnsHopkins Univ.)

[J. Phys. B: At., Mol. Opt. Phys. 37, 4551–4560 (2004)]

Five-fold differential cross sections for electron-impact double ionization of the 3s electrons of magne-sium have been calculated in the second Born approx-imation in the impulsive regime. Comparing theseresults with calculations carried out in the first Bornapproximation demonstrates the dominant contributionof the second Born term. The second Born calculationshows that contribution of the two-step 2 (TS2) processbecomes large under the condition where sequentialbinary collisions on the Bethe ridge can occur. Theeffect of electron correlation in the initial target state isalso examined by using a configuration interactionwavefunction.

IX-R-4 Electron Momentum Spectroscopy ofValence Satellites of Neon

WATANABE, Noboru1; KHAJURIA, Yugal2;TAKAHASHI, Masahiko1; UDAGAWA, Yasuo1

(1IMS and Tohoku Univ.; 2IMS and IIT Madras)

[J. Electron Spectrosc. Relat. Phenom. 142, 325–334(2005)]

Electron momentum spectroscopy (EMS) study ofthe neon valence satellites is reported. The experimentswere performed at impact energies of 1250, 1450 and1670 eV using a multichannel spectrometer that featureshigh sensitivity. Binding energy spectra up to 100 eV


IX-R Electronic Structure and Collision Dynamics of Atomsand Molecules Studied by Electron Impact at Large

Momentum Transfer

Binary (e,2e) or electron momentum spectroscopy (EMS) is a high-energy electron-impact ionization experimentat large momentum transfer. The method involves coincident detection of the two outgoing electrons, allowing oneto measure electron momentum densities for individual transitions or to look at molecular orbitals in momentumspace. For molecular targets, however, EMS has long been plagued by the fact that the conventional (e,2e) experi-ments measure averages over all orientations of gaseous targets; the spherical averaging results in enormous loss ofversatile information on the target electronic structure, anisotropy of the target wavefunction in particular. Toovercome the historical experimental difficulty, we have proposed the (e,2e+M) method based on axial recoilfragmentation of the residual molecular ion and molecular frame (e,2e) cross sections have been successfully mea-sured for the first time. Further attempts along this line are now in progress, opening the door for detailed studies ofbound electronic wavefunctions of molecules as well as of stereodynamics of electron-molecule collisions.

and momentum profiles for the 2p–1 and 2s–1 primarytransitions as well as the satellites are presented. Theresults are used to examine impact energy dependenceof the relative intensities and shapes of the satellitemomentum profiles. The results are also used to deter-mine symmetries and spectroscopic factors of the satel-lites, and are compared with the previous experimentsby EMS and photoelectron spectroscopy and sophisti-cated theoretical calculations. The present study haslargely resolved controversies in the previous studies.

IX-R-5 Theoretical Fine Spectroscopy withSymmetry-Adapted-Cluster Configuration-Interaction Method: Outer- and Inner-ValenceIonization Spectra of Furan, Pyrrole, andThiophene

EHARA, Masahiro1; OHTSUKA, Yuhki1;NAKATSUJI, Hiroshi1; TAKAHASHI, Masahiko2;UDAGAWA, Yasuo2

(1Kyoto Univ.; 2IMS and Tohoku Univ.)

[J. Chem. Phys. 122, 234319 (10 pages) (2005)]

Theoretical fine spectroscopy has been performedfor the valence ionization spectra of furan, pyrrole, andthiophene with the symemtry-adapted-cluster configura-tion-interaction general-R method. The present methoddesribed that the π1 state interacts with the π3

–2π*,π2

–2π*, and π2–1π3

–1π* shake-up states provoding thesplit peaks and the outer-valence satellites, both ofwhich are in agreement with the experiments. The inten-sity distributions were analyzed in detail for the inner-valence-region. In particular, for furan, theoreticalintensities were successfully compared with the inten-sity measured by the electron momentum spectroscopy.The interactions of the 3b2 and 5a1 states with theshake-up states were remarkable for furan and pyrrole,while the 4b2 state of thiophene had relatively largeintensity.

IX-R-6 Observation of a Molecular Frame (e,2e)Cross Section: An (e,2e+M) Triple CoincidenceStudy on H2

TAKAHASHI, Masahiko1; WATANABE, Noboru1;KHAJURIA, Yugal2; UDAGAWA, Yasuo1; ELAND,John H. D.3(1IMS and Tohoku Univ.; 2IMS and IIT Madras; 3IMSand Oxford Univ.)

[Phys. Rev. Lett. 94, 213202 (4 pages) (2005)]

We report the first experimental results showingtransition-specific anisotropy of molecular frame (e,2e)cross sections. Vector correlations between the twooutgoing electrons and the fragment ion have been mea-sured for specific ionization-excitation processes of H2.The results enable us to obtain molecular frame (e,2e)cross sections for transitions to the 2sσg and 2pσuexcited states of H2

+, thereby making stereodynamics ofthe electron-molecule collisions directly visible.

IX-R-7 (e,2e) and (e,3–1e) Studies on DoubleProcesses of He at Large Momentum Transfer

WATANABE, Noboru1; KHAJURIA, Yugal2;TAKAHASHI, Masahiko1; UDAGAWA, Yasuo1;VINITSKY, Pavel S.3; POPOV, Yuri V.3;CHULUUNBAATAR, Ochbadrakh4; KOZAKOV,Konstantin A.3(1IMS and Tohoku Univ.; 2IMS and IIT Madras;3Moscow State Univ.; 4JINR)

[Phys. Rev. A 72, 32705 (11 pages) (2005)]

The double processes of He in electron-impact ioni-zation, single-ionization with simultaneous excitationand double-ionization, have been studied at large mo-mentum transfer using an energy- and momentum-dispersive binary (e,2e) spectrometer. The experimenthas been performed at an impact energy of 2080 eV inthe symmetric noncoplanar geometry. In this way wehave achieved a large momentum transfer of 9 a.u., avalue that has never been realized so far for the study ondouble-ionization. The measured (e,2e) and (e,3–1e)cross sections for transitions to the n = 2 excited state ofHe+ and to doubly ionized He2+ are presented as nor-malized intensities relative to that to the n = 1 groundstate of He+. The results are compared with first-orderplane-wave impulse approximation (PWIA) calculationsusing various He ground-state wavefunctions. It isshown that shapes of the momentum-dependent (e,2e)and (e,3–1e) cross sections are well reproduced by thePWIA calculations only when highly correlated wave-functions are employed. However, noticeable discrepan-cies between experiment and theory remain in magni-tude for both the double processes, suggesting impor-tance of higher-order effects under the experimentalconditions examined as well as of acquiring more com-plete knowledge of electron correlation in the target.

IX-R-8 Electron Momentum Spectroscopy ofthe HOMO of Acetone

CHO, Tegyon1; TAKAHASHI, Masahiko2;UDAGAWA, Yasuo2

(1Tohoku Univ.; 2IMS and Tohoku Univ.)

[J. Photochem. Photobiol. in press]

Electron momentum profiles of the HOMO ofacetone have been measured under experimental condi-tions where a use of the plane-wave impulse approxima-tion is justified. A double peak is observed in the experi-mental profile and it was found that calculated profilesby the use of the standard basis set always under-estimate the magnitude of the low momentum peak.Possible origins of the discrepancies between the calcu-lated and measured profiles are examined, leading to animproved agreement by modifying the exponents ofdiffuse functions employed.


IX-R-9 (e,3–1e) Reactions at Large MomentumTransfer: The Plane-Wave Second BornApproximation

VINITSKY, Pavel S.1; POPOV, Yuri V.1;KOZAKOV, Konstantin A.1; WATANABE,Noboru2; TAKAHASHI, Masahiko2

(1Moscow State Univ.; 2IMS and Tohoku Univ.)

[Phys. Rev. A to be submitted]

We consider theoretically symmetric (e,3–1e) reac-tions of He atom at large momentum transfer. Forevaluating the corresponding four-fold differential crosssections, a theory based on the re-normalized plane-wave second Born approximation (SBA) is developed.The numerical SBA calculations for both coplanar andnon-coplanar symmetric geometries are performed andcompared with experiments.

IX-R-10 Binary (e,2e) Study on Xe: MomentumProfile for the 4d Orbital Revisited

KHAJURIA, Yugal1; TAKAHASHI, Masahiko2;WATANABE, Noboru2; UDAGAWA, Yasuo2;YOSHINO, Tae3; SAKAI, Yasuhiro3;MUKOYAMA, Takeshi4(1IMS and IIT Madras; 2IMS and Tohoku Univ.; 3TohoUniv.; 4Kansai Gaidai Univ.)

[J. Phys. B: At. Mol. Opt. Phys. to be submitted]

Binary (e,2e) cross sections have been measured forXe using an energy- and momentum-dispersive multi-channel spectrometer at impact energy of 2055 eV.Assuming that the Xe 5p ionization process can bedescribed by the distorted-wave Born approximation(DWBA), the experimental momentum profile for the4d orbital was placed on an absolute scale. The abso-lute-scale Xe 4d experiment has been compared withDWBA calculations using the Hartree-Fock and Dirac-Fock wavefunctions, in order to exploit relativisticeffects in both shape and intensity of momentum profile.Although DWBA/DF has been found to give betterdescription than DWBA/HF, noticeable discrepanciesbetween experiment and theory still remain.

IX-R-11 Binary (e,2e) Study on Inner ShellOrbitals of Ar and Xe

MIYAKE, Yusuke1; SHIBUYA, Masahiro1;TAKAHASHI, Masahiko2; WATANABE, Noboru2;

UDAGAWA, Yasuo2; SAKAI, Yasuhiro3;MUKOYAMA, Takeshi4(1Tohoku Univ.; 2IMS and Tohoku Univ.; 3Toho Univ.;4Kansai Gaidai Univ.)

[J. Phys. B: At. Mol. Opt. Phys. to be submitted]

Binary (e,2e) experiments were performed on Xe 4p,4s and Ar 2p, 2s orbitals. The results are compared withdistorted-wave Born approximation calculations usingthe Hartree-Fock and Dirac-Fock wavefunctions, inorder to exploit relativistic effects in momentum profile.Furthermore, for Xe the experiments have revealed abroad band at around 100 eV, which has not been foundby photoelectron spectroscopy. The band has beenassigned as giant resonance of Xe 4d in the sequentialtwo collisions of the projectile with the target electrons.

IX-R-12 Construction of a New (e,2e+M)Apparatus for Complete Imaging of MolecularOrbitals

TAKAHASHI, Masahiko1; WATANABE, Noboru1;SHIBUYA, Masahiro2; MIYAKE, Yusuke2;UDAGAWA, Yasuo1; MIZUTANI, Nobuo; SUZUI,Mitsukazu; MIURA, Kazuhiro2; YANAGIDA,Satomi2; MINEGISHI, Kouji2; JAGUTZKI,Ottmar3; DÖRNER, Reinhard3

(1IMS and Tohoku Univ.; 2Tohoku Univ.; 3Univ.Frankfurt)

We have constructed a new electron-electron-frag-ment ion triple coincidence apparatus for completeimaging of molecular orbitals. The major sections of theapparatus are a chamber equipped with a 2300 L/s turbomolecular pump, an electron gun, a spherical analyzerfollowed by a hexagonal delay-line position-sensitivedetector which covers the full 2π azimuth of the twooutgoing electrons emerging at the scattering angle of45°, a velocity imaging system to detect all of parentand fragment ions from the 4π solid angle, and datagathering electronics. The electron gun and sphericalanalyzer have been developed at the machine shop ofthe Tohoku University, while the chamber and the datagathering electronics have been developed at the equip-ment development center of IMS. This project aims atfully extending our preliminary (e,2e+M) studies [M.Takahashi et al., J. Phys. Chem. Solids 65, 2055 (2004);J. Electron Spectrosc. Relat. Phenom. 141, 83 (2004);Phys. Rev. Lett. 94, 213202 (2005)], which have made itpossible to perform molecular frame (e,2e) spectroscopyfor the first time.


IX-S Electronic Structure and Collision Dynamics of Atomsand Molecules Studied by Photon Impact

The group takes another, photon-impact, approach to issues of electronic structure and collision dynamics, sincephoton-impact and electron-impact or photoelectric effects and Compton scattering are complementary to eachother.

IX-S-1 Inner-Shell Photoelectron AngularDistributions from Fixed-in-Space OCSMolecules

GOLOVIN, Alexander V.1,2; ADACHI, Junichi1,3,4;MOTOKI, Souhei1; TAKAHASHI, Masahiko5;YAGISHITA, Akira1,3

(1KEK-PF; 2St. Petersburg State Univ.; 3Univ. Tokyo;4IMS; 5IMS and Tohoku Univ.)

[J. Phys. B: At. Mol. Opt. Phys. 38, L63–L68 (2005)]

The photoelectron angular distributions (PADs) forthe OCS O 1s, C 1s and S 2p1/2, 2p3/2 ionization havebeen measured in the shape resonance region. Theexperimental results have been compared with multiplescattering Xα calculations. It is found that the positionof an ionized atom plays a significant role. For a centralposition (C 1s ionization) the PAD is relatively symmet-ric. In the case of S 2p and O 1s ionization, electrons areemitted highly preferentially in a solid cone directedfrom the molecular centre to the respective S or O atom.For the OCS O 1s ionization the S–C fragment plays avery effective role as a ‘scatterer’ in the shape reso-nance region nearly all intensity in PAD is concentratedin the lobe between θ = 50° and 80°, but not along themolecular axis.

IX-S-2 Coincidence Velocity ImagingApparatus for the Study of AngularCorrelations between Photoelectrons andPhotofragments

HOSAKA, Kouichi1; ADACHI, Junichi1,2,3;GOLOVIN, Alexander V.2,4; TAKAHASHI,Masahiko5; WATANABE, Noboru5; YAGISHITA,Akira1,2

(1Univ. Tokyo; 2KEK-PF; 3IMS; 4St. Petersburg StateUniv.; 5IMS and Tohoku Univ.)

[J. Electron Spectrosc. Relat. Phenom. submitted]

A new apparatus of coincidence velocity mappinghas been developed for studies on inner-shell photoioni-zation dynamics of molecules. It achieves velocityimaging for electrons and ions simultaneously, andkeeps the time focusing. To demonstrate the perfor-mance of the new apparatus, some examples, photo-electron angular distributions from Ne atoms and ran-domly oriented NO molecules, photoion angular distri-butions from CO molecules, and photoelectron angulardistributions form fixed-in-space CO and NO mol-ecules, are reported.

IX-S-3 Non-Dipole Effects in the AngularDistribution of Photoelectrons from the K-Shellof N2 Molecule

HOSAKA, Kouichi1; ADACHI, Junichi1,2,3;GOLOVIN, Alexander V.2,4; TAKAHASHI,Masahiko5; TERAMOTO, Takahiro1;WATANABE, Noboru5; YAGISHITA, Akira1,2;SEMENOV, Sergei K.6; CHEREPKOV, Nikolai A.6(1Univ. Tokyo; 2KEK-PF; 3IMS; 4St. Petersburg State

Univ.; 5IMS and Tohoku Univ.; 6State Univ. AerospaceInstrum.)

[J. Phys. B: At. Mol. Opt. Phys. submitted]

Measurements and calculations of contribution ofthe non-dipole terms in the angular distribution ofphotoelectrons from the K-shell of randomly orientedN2 molecules are reported. The angular distributionshave been measured in the plane containing the photonpolarization and the photon momentum vectors oflinearly polarized radiation. Calculations have beenperformed in the relaxed core Hartree-Fock approxima-tion with a fractional charge, and many-electron correla-tions were taken into account in the random phaseapproximation. Both theory and experiment show thatthe non-dipole terms are rather small in the photonenergy region from the ionization threshold of the K-shell up to about 70 eV above it. From the theory itfollows that the non-dipole terms for the individualshells of 1σg and 1σu are considerably large, thereforemeasurements resolving the contributions of the 1σg and1σu shells are desirable.

IX-S-4 Direct Observation of a SymmetryLowering in Core-Electron Ionization for HighlySymmetric Molecules

HOSAKA, Kouichi1; ADACHI, Junichi1,2,3;GOLOVIN, Alexander V.2,4; TAKAHASHI,Masahiko5; TERAMOTO, Takahiro1;WATANABE, Noboru5; YAGISHITA, Akira1,2

(1Univ. Tokyo; 2KEK-PF; 3IMS; 4St. Petersburg StateUniv.; 5IMS and Tohoku Univ.)

The symmetry lowering occurs quite often in theionization of a core electron of equivalent constituent-atoms for highly symmetric molecules since the core-hole states of those molecules are generally quasi-degenerate and therefore couple over non-totally sym-metric vibrational modes. Such couplings, referred asquasi-Jahn-Teller couplings, have been clearly investi-gated for the most basic example of CO2; the relationbetween the symmetry lowering and core-hole localiza-tion has been proved. The symmetry lowering whichremoves the equivalence of two oxygen atoms causes afundamental quantum mechanical question; is it pos-sible to decide whether the core hole is localized on theright oxygen atom or on the left? Here we report thedirect observation of the symmetry lowering of the CO2induced by O1s photoionization.


IX-T-1 Deep Insight into a Valence Hole inOrganic Semiconductors: High-ResolutionUltraviolet Photoemission Study

KERA, Satoshi; UENO, Nobuo1

(1Chiba Univ.)

[IPAP Conf. Ser. 6, 51–56 (2005)]

We have succeeded to observe a very sharp highestoccupied molecular orbital (HOMO) band for orientedthin films of various phthalocyanines prepared ongraphite via high-resolution ultraviolet photoelectronspectroscopy. Hole-vibration couplings can be resolvedeven for films of large π-conjugated molecules. The finestructure would give us lots information on “hidden”properties in organic-based devices, such as molecular-vibration related carrier dynamics, intermolecular inter-action, and molecule-substrate interaction. Moreover, itwas found that the observed binding energy position ismuch affected by inhomogeneity of the film withdifferent molecular orientations, leading to a broadeningof the HOMO bandwidth.

IX-T-2 UPS Fine Structures of HighestOccupied Band in Vanadyl-PhthalocyanineUltrathin Film

FUKAGAWA, Hirohiko1; YAMANE, Hiroyuki1;KERA, Satoshi; OKUDAIRA, K. Koji1; UENO,Nobuo1

(1Chiba Univ.)

[J. Electron Spectrosc. 144-147, 475–478 (2005)]

Ultraviolet photoelectron spectra were measured forvanadyl phthalocyanine (VOPc) ultrathin films preparedon graphite to study effects of the molecular orientationand the electric dipole layer on the organic electronicstates. VOPc has a permanent electric dipole perpen-dicular to the molecular plane, hence a well-definedelectric dipole layer could be intentionally prepared byusing the oriented monolayer. The observed binding-energy difference of the highest occupied molecularorbital (HOMO) bands between the oriented monolayer

and the double layer was found to agree with thevacuum level shift, leading to a conclusion that themolecular energy level with respect to the substrateFermi level is changed when the molecule is in theelectric dipole layer.

IX-T-3 Fine Structure of the Highest OccupiedBand in OTi-Phthalocyanine Monolayer

YAMANE, Hiroyuki1; FUKAGAWA, Hirohiko1;HONDA, Hiroyuki1; KERA, Satoshi; OKUDAIRA,K. Koji1; UENO, Nobuo1

(1Chiba Univ.)

[Synth. Met. 152, 297–300 (2005)]

Ultraviolet photoelectron spectra were measured forultrathin films of OTi-phthalocyanine (OTiPc), whichhas an electric dipole perpendicular to the molecularplane, prepared on highly oriented pyrolytic graphite inorder to study effects of the molecular orientation andthe electric dipole layer on the organic electronic states.For the as-grown films, the observed highest occupiedmolecular orbital (HOMO) band consists of two promi-nent peaks that can be assigned to different molecularorientations. For the oriented monolayer obtained byannealing the as-grown film, we detected a very sharpHOMO band at 290 K. The binding-energy (EB) differ-ence between the HOMO bands of the as-grown andannealed films was found to agree with the shift in thevacuum level. For the oriented monolayer, the observedsharp HOMO band involves at least four componentsthat are ascribed to the coupling between the HOMOhole and the molecular vibration. Upon cooling thesample to 95 K, the HOMO bandwidth became sharperthan that at 290 K. From the peak fitting using Voigtfunction, additional components are expected in theHOMO band at 95 K. Moreover, we detected the EBshift in the HOMO band for the oriented monolayerupon cooling, which can be originated from decrease inthe HOMO-hole screening due to the change in the filmstructure and/or the molecule-substrate interaction.

IX-T-4 Hole/Vibration Coupling of the HighestOccupied Band in Pentacene Thin Film


IX-T Study of Electronic Structure of Organic Thin Film andOrganic/Inorganic Interface

Organic semiconductors have attracted much interest due to their highly potential, flexibility, electronic andoptical properties, and their considerable promise in molecular device technologies. To clarify the electronicproperties at the organic/organic and organic/metal interface, various characterization techniques such as high-resolution ultraviolet photoemission spectroscopy (UPS) and near-edge x-ray absorption fine structure (NEXAFS)have been performed for organic thin film systems, because origin of the energy position, band shape and bandwidth of UPS spectra are keys to understand the interface properties such as the energy level alignment at theinterface, intermolecular or molecule-substrate interactions, and carrier transfer/transport process. Especially,vibronic coupling and lifetime of a hole created in the highest occupied molecular orbital (HOMO) state in theorganic thin film play a crucial role in the hole transport through the film and the electron injection from an electrodeto the ionized molecule. The HOMO band in UPS spectra in principle involves such information about the hole, andthus offers a variety of key information that is necessary to unravel fundamental mechanism in carrier dynamics inorganic devices.


YAMANE, Hiroyuki1; NAGAMATSU, Shin-ichi1;FUKAGAWA, Hirohiko1; KERA, Satoshi;FRIEDLEIN, Rainer2; OKUDAIRA, K. Koji1;UENO, Nobuo1

(1Chiba Univ.; 2Linköping Univ.)

[Phys. Rev. B 72, 153412 (4 pages) (2005)]

The hole-vibration coupling of the highest occupiedstate in pentacene thin films on graphite is studied byhigh-resolution ultraviolet photoelectron spectroscopy.Vibration satellites in the film show a take-off-angledependence, indicating that the Frank-Condon principleis not strictly satisfied in this system. They are moreintense than in the gas phase and the vibrational energyin the film is slightly lower than that in the gas phase.This demonstrates that the reorganization energy inpentacene thin films is slightly larger than that estimatedfrom the photoelectron spectrum of free pentacenemolecules. Furthermore, it is pointed out that the elec-tron hopping in the low-temperature film may occur inthe femtosecond scale before the electronic polarizationof the surrounding medium is completed.

IX-T-5 Quantitative Analysis of PhotoelectronAngular Distribution of a Single DomainOrganic Monolayer Film: NTCDA on GeS(001)

KERA, Satoshi; TANAKA, Shinji1; YAMANE,Hiroyuki1; YOSHIMURA, Daisuke2; OKUDAIRA,K. Koji1; SEKI, Kazuhiko3; UENO, Nobuo1

(1Chiba Univ.; 2IMS and Nagoya Univ.; 3Nagoya Univ.)

[Chem. Phys. in press]

Angle-resolved photoelectron spectra were mea-sured for a single-crystal monolayer film of naphtha-lene-1,4,5,8-tetracarboxylic dianhydride (NTCDA)prepared on a cleaved GeS(001) surface using synchro-tron radiation. The observed photoelectron angulardistributions were analyzed by a calculation using thesingle-scattering approximation combined with molecu-lar orbital calculation. With the help of the low-energyelectron diffraction pattern, the structure of the NTCDAmonolayer on GeS(001) was estimated quantitatively.

IX-T-6 UPS Study of VUV-Photodegradation ofPolytetrafluoroethylene (PTFE) Ultrathin Filmby Using Synchrotron Radiation

ONO, Masaki1; YAMANE, Hiroyuki1;FUKAGAWA, Hirohiko1; KERA, Satoshi;YOSHIMURA, Daisuke2; OKUDAIRA, K. Koji1;MORIKAWA, Eiji3; SEKI, Kazuhiko4; UENO,Nobuo1

(1Chiba Univ.; 2IMS and Nagoya Univ.; 3CAMD;4Nagoya Univ.)

[Nucl. Instrum. Methods Phys. Res., Sect. B 236,377–382 (2005)]

The VUV-photodegradation of polytetrafluoro-ethylene (PTFE) ultra-thin film was studied by ultra-violet photoelectron spectroscopy and quadrupole mass

spectrometry. These results were compared with theprevious photodegradation studies of the poly-vinylidenefluoride (PVDF) and polyethylene (PE). Gen-eration of new peak, π-band originated from the C=Cbond, was observed in the low binding energy region ofthe UPS spectra in both PVDF and PE during the photo-degradation. In contrast, no new peak generation wasobserved in the UPS of the photodegraded PTFE. Massspectrometry analysis also suggested that the C=C bondgeneration is not a major mechanism in the VUV photo-degradation of PTFE.

IX-T-7 Site-Specific Ion Desorption ofFluorinated Phthalocyanine Studied withElectron-Ion Coincidence Spectroscopy

OKUDAIRA, K. Koji1; WATANABE, Takahiro1;KERA, Satoshi; KOBAYASHI, Eiichi2; MASE,Kazuhiko2; UENO, Nobuo1

(1Chiba Univ.; 2AIST)

[J. Electron Spectrosc. 144-147, 464–464 (2005)]

Auger electron photo-ion coincidence (AEPICO)and Auger spectra of fluorinated copper phthalocyanine(F16CuPc) were observed to study the mechanism of thesite-specific ion desorption. From the photon energydependence of Auger electron spectra at fluorine (F) K-edge region, it is found that the spectator-Auger shift athν = 691.4 eV is about 2 eV. To estimate the contribu-tion of spectator-Auger component to the Auger spectra,the difference Auger spectra were obtained by subtract-ing the Auger spectrum above F 1s ionization energyfrom observed Auger spectra. AEPICO yield spectra forF+ at hν = 691.4 eV gives a large intensity at Ekin = 650eV. The electron kinetic energy position of this intenseF+ AEPICO peak agrees with that of the differenceAuger spectra, indicating that the most probable mecha-nism for F+ ion desorption induced by the transitionfrom F1s to σ(C–F)* is the spectator-Auger-stimulatedion desorption.

IX-T-8 Polarized Near-Edge X-Ray-AbsorptionFine Structure Spectroscopy of C60-Functionalized 11-Amino-1-Undecane ThiolSelf-Assembled Monolayer: MolecularOrientation and Evidence for C60 Aggregation

PATNAIK, Archita1; OKUDAIRA, K. Koji1; KERA,Satoshi; SETOYAMA, Hiroyuki1; MASE,Kazuhiko2; UENO, Nobuo1

(1Chiba Univ.; 2AIST)

[J. Chem. Phys. 122, 154703 (9 pages) (2005)]

Near-edge x-ray-absorption fine structure (NEXA-FS) spectroscopy was adopted to probe the unoccupiedelectronic states of C60 anchored onto an organizedassembly of 11-amino-1-undecane thiol on Au(111).The polarization dependence of the intensity of π* reso-nance associated with C60 π network revealed the self-assembled monolayer (SAM) system to be oriented withan average molecular tilt angle of 57° with respect to thesurface normal. Invoking the absence of solid-state band

dispersion effects and in comparison to solid C60 and/or1-ML C60/Au(111), the electronic structure of theresulting assembly was found dominated by spectralposition shift and linewidth and intensity changes of thelowest unoccupied molecular orbital (LUMO), LUMO+1, and LUMO+2 orbitals. The latter implied hybridiza-tion between N Pz of -NH2 group of thiolate SAM and πlevels of C60, resulting in a nucleophilic addition with achange in the symmetry of C60 from Ih to C1 in theSAM. Occurrence of a new feature at 285.3 eV in theNEXAFS spectrum, assigned previously to π* graphiticLUMO, signified the formation of aggregated clusters,(C60)n of C60 monomer. Low tunneling current scanningtunneling microscopy confirmed them to be sphericaland stable aggregates with n ~ 5.



IX-U-1 Successful Commissioning of New RFCavity

MOCHIHASHI, Akira; KATOH, Masahiro;HOSAKA, Masahito; YAMAZAKI, Jun-ichiro;HAYASHI, Kenji; TAKASHIMA, Yoshifumi1(1Nagoya Univ.)

We have built a new main RF accelerating cavity forthe UVSOR-II electron storage ring. The new cavity cangenerate RF voltage of 150 kV without replacing thehigh power RF transmitter whose maximum outputpower is 20 kW. The cavity was installed in a shortstraight section in the spring 2005. The design RFvoltage of 150 kV was soon achieved in the high-powertest operation without electron beam. After the highpower test operation, the test operation with electronbeam was started. By carefully observing the pressurerise in the cavity, we have decided to start the useroperation with a moderately high RF accelerating RFvoltage of 100 kV, which is twice higher than before.After the vacuum is completely recovered, the operationwith the design voltage of 150 kV will be started. Thesehigh values of the accelerating voltage have made thelow emittance operation possible without reducing the

beam lifetime. Since May 2005, the UVSOR-II electronstorage ring has been operated with a small emittance of27 nm-rad for users.

IX-U-2 Ion Trapping Phenomena at UVSOR-II

MOCHIHASHI, Akira; KATOH, Masahiro;HOSAKA, Masahito; YAMAZAKI, Jun-ichiro;HAYASHI, Kenji; TAKASHIMA, Yoshifumi1;HORI, Yoichiro2

(1Nagoya Univ.; 2KEK)

We have observed the dependence of the verticalbetatron tune on the vacuum condition on the UVSOR-II electron storage ring. We changed the vacuum condi-tion artificially by turning off the vacuum pumps. Thebetatron tune was measured by RF-KO method. Duringthe experiment, the storage ring was operated in multi-bunch filling mode, in which successive twelve RFbuckets were filled with electrons and other four bucketswere kept empty. This result strongly suggested that thenon-linear electric field produced by the ions trapped bythe electron beam caused the betatron tune shift. Wehave observed betatron tune shifts were consistent withthe theoretical predictions.

UVSOR Facility

IX-U Development of the UVSOR Light Source

IX-V Researches by the Use of UVSOR

IX-V-1 Development of Velocity ImagingSpectrometer for Observing Negative FragmentIons

HIKOSAKA, Yasumasa; SHIGEMASA, Eiji

[J. Electron Spectrosc. Relat. Phenom. 148, 5 (2005)]

A velocity imaging spectrometer has been developedto observe negative ions from molecular ion-pair disso-ciation. The imaging spectrometer furnishes with a pairof permanent magnets. The formed magnetic field effec-tively prevents the electrons’ arrivals to the detector,without seriously affecting negative ions’ flights. Theperformance of the imaging spectrometer is demon-strated in the observations of photoelectrons from O2and He, and O– from O2. Sample results on negative ionformation from O2 and N2O, prove that the presentimaging method provides useful information on theassignments of superexcited states and the dynamicalproperties of ion-pair dissociation.

IX-V-2 Dynamics of Double Photoionizationnear the Ar 2p Threshold Investigated byThreshold Electron-Auger ElectronCoincidence Spectroscopy

LABLANQUIE, Pascal1; SEINERMAN, Sergei2;PENENT, Francis3; AOTO, Tomohiro4;HIKOSAKA, Yasumasa; ITO, Kenji4(1LURE; 2St. Petersburg State Maritime Tech. Univ.;3LCPMR; 4KEK)

[J. Phys. B 38, L9 (2005)]

Threshold electron–Auger electron coincidencespectroscopy measurements were carried out near theAr 2p thresholds. Such a method allows us, for the firsttime, to observe the threshold electron yields associatedwith the selected final states of the Ar2+ ion: 3p4(1D2),3p4(1S0), 3p4(3P) resulting from the 2p hole Augerdecay. All the spectra reveal strong PCI distortion.Comparison with calculations carried out in the frame-work of a quantum-mechanical PCI model allows us toclarify the mechanisms and the dynamics of thresholdelectron production. In the 3p4(1D2) and 3p4(1S0) chan-nels, contribution to the threshold electron yield comesessentially from the PCI retardation of slow photo-electrons. In the 3p4(3P) final state channel, an addition-al process of valence multiplet decay of the 3p4(1D2)6dstate plays a role at and below the L2, L3 thresholds.

IX-V-3 Origin of Threshold Electrons Producedin Decay of the Xe 4d–1np Resonance

AOTO, Tomohiro1; HIKOSAKA, Yasumasa;HALL, Richard2; PENENT, Francis2;LABLANQUIE, Pascal3; ITO, Kenji1(1KEK; 2DIAM; 3LURE)

[J. Electron Spectrosc. Relat. Phenom. 142, 319 (2005)]

Coincidence spectra of energetic electrons withthreshold electrons were measured following photo-excitation of the Xe 4d3/2,5/2 → np resonances, in orderto investigate the origin of threshold electrons, and themechanism leading to formation of the Xe2+ 5p–2 and5s–15p–1 final states. A two-step decay process wasobserved in the production of Xe2+ 5p–2(1D) followingdecay of the 7p resonance, where the intermediate stateis Xe+* 5p–2(1S)8p that autoionizes emitting a pseudo-threshold electron. This process was confirmed in atime-of-flight analysis of the coincidence spectra of theenergetic electrons with the threshold photoelectrons. Itis suggested that a similar two-step process also contrib-utes to the population of excited Xe2+ states and is themain origin for the production of threshold electrons indecay of the 4d–1 np resonances.

IX-V-4 Coincidence Auger Spectroscopy

PENENT, Francis1,2; LABLANQUIE, Pascal3;HALL, Richard2; PALAUDOUX, Jerome1; ITO,Kenji4; HIKOSAKA, Yasumasa; AOTO,Tomohiro4; ELAND, John H. D.5(1LCPMR; 2DIAM; 3LURE; 4KEK; 5PTCL)

[J. Electron Spectrosc. Relat. Phenom. 144-147, 7(2005)]

Auger electron spectroscopy (AES) and photo-electron spectroscopy (PES) are (with X-ray emissionspectroscopy, XES) powerful analytical tools formaterial science and gas phase studies. However, theinterpretation of Auger spectra can be very difficult dueto the number and complexity of the involved processes.A deeper analysis, that allows a better understanding ofrelaxation processes following inner shell ionization, ispossible with coincidence Auger spectroscopy. Thismethod gives a new insight into electron correlation andallows disentangling of complex Auger electron spectra.In this paper, we present some examples related to gasphase coincidence Auger electron spectroscopy usingsynchrotron radiation. The detection in coincidence ofan Auger electron with a threshold photoelectron pres-ents two main advantages which are good energy reso-lution and high coincidence count rates. This techniquehas also provided new results on double Auger decayprocesses. A further qualitative breakthrough has beenmade with the development of a new experimental set-up based on a magnetic bottle time-of-flight electronspectrometer. This opens up the field of multi-electroncoincidence spectroscopy and allows a most detailedanalysis with characterization of all possible decaypathways following inner shell ionization.

IX-V-5 Collision Dynamics of the Kr8+ + N2System Studied by a Multi-CoincidenceTechnique

KANEYASU, Tatsuo; AZUMA, Toshiyuki1;OKUNO, Kazuhiko1

(1Tokyo Metropolitan Univ.)

[J. Phys. B 38, 1341 (2005)]

We have developed a multi-coincidence technique tostudy MCI-molecule collisions. Using this technique,complicated reaction processes and collision dynamicsin Kr8+ + N2 collisions have been successfully revealedin the energy region below 200 eV/u. The reactionprocesses in the single-, double-, triple- and quadruple-charge changing collisions are resolved and three low-energy collision phenomena, ‘peak-shifting’ of molecu-lar ions, ‘peak-splitting’ and ‘anisotropic fragmentation’of fragment ion pairs, are found in the time-of-flightspectra of target ions. By careful analysis of kinematicsof all the products, it is concluded that the charge trans-fer in the Kr8+ + N2 collisions is dominated by multi-electron capture processes followed by electron emis-sion and the collision dynamics is characterized by thetransverse momentum transfer from the ion to themolecule and the appearance of the ‘anisotropicfragmentation.’

IX-V-6 Collision Dynamics of MCI-MoleculeSystems Studied by Multi-CoincidenceTechnique

KANEYASU, Tatsuo; AZUMA, Toshiyuki1;OKUNO, Kazuhiko1

(1Tokyo Metropolitan Univ.)

[Nucl. Instrum. Methods Phys. Res., Sect. B 235, 352(2005)]

Collision dynamics and reaction processes in chargetransfer collisions of Kr8+ + N2 below 200 eV/u havebeen studied. We used a multi-coincidence techniquewhich enables us to obtain kinematic information forboth the fragment ions and the scattered projectile. Thecollision phenomena observed in the time-of-flightspectra of target ions are well clarified in considerationof the kinematics in colliding particles. We found ananisotropy in charge-unbalanced fragmentation channelsat lower collision energy. The anisotropic behaviorbecomes significant not only with decreasing thecollision energy but also with increasing the chargeimbalance of the fragment ion-pair. The collisiondynamics in the Kr8+ + N2 system is characterized bythe transverse recoil momentum and the anisotropicfragmentation.

IX-V-7 Optical Investigations of the Clathrate α-Eu8Ga16Ge30

SICHELSCHMIDT, Joerg1; VOEVODIN,Vladimir1; PACHECO, J.1; GRIN, Yuri1;STEGLICH, Frank1; NISHI, Tatsuhiko2; KIMURA,Shin-ichi

180 RESEARCH ACTIVITIES IX UVSOR Facility

(1Max-Planck Inst.; 2SOKENDAI)

[Eur. Phys. J. B 46, 363–366 (2005)]

We performed measurements of the optical reflec-tivity in the energy range 0.007–30 eV on the clathrate-VIII type compound α-Eu8Ga16–xGe30–x in order toinvestigate its electronic band structure. The very lowcharge carrier concentration as well as ferromagneticordering of the divalent Eu ions below 10.5 K charac-terize the spectra at photon energies below ~0.4 eV inaccordance with the results of band structure calcu-lations. Disorder induced bound states have beenidentified to affect the optical conductivity at energiesbetween 10 and 100 meV.

IX-V-8 Influence of Cage Distortions on theElectronic Structure and Optical Properties ofBa6Ge25

ZEREC, Ivica1; CARRILLO-CABRERA, Wilder1;VOEVODIN, Vladimir1; SICHELSCHMIDT,Joerg1; STEGLICH, Frank1; GRIN, Yuri1;YARESKO, Alexander1; KIMURA, Shin-ichi(1Max-Planck Inst.)

[Phys. Rev. B 72, 045122 (7 pages) (2005)]

Measurements of the optical conductivity onBa6Ge25 reveal a shift of optical spectral weightstowards higher energies, as temperature is loweredbelow the structural phase transition. This behavior maybe understood from the structural modifications revealedfrom the new structure refinements of x-ray diffractiondata from high quality single crystals. Apart from Baatoms, some Ge cage atoms are also shifted into distantsplit sites below the phase transition. In this way onecovalent bond is broken between the corresponding Geatoms and they become threefold bonded. Electronicband structure calculations for the low symmetryordered model show that the bond breaking causes ashifting of three bands from the conduction to thevalence region. This leads to a shifting of optical spect-ral weights towards higher energies, which is in agree-ment with the experimental data.

IX-V-9 Indirect and Direct Energy Gaps inKondo Semiconductor YbB12

OKAMURA, Hidekazu1; MICHIZAWA, Takahiro1;NANBA, Takao1; KIMURA, Shin-ichi; IGA,Fumitoshi2; TAKABATAKE, Toshiro2

(1Kobe Univ.; 2Hiroshima Univ.)

[J. Phys. Soc. Jpn. 74, 1954–1957 (2005)]

The optical conductivity [σ(ω)] of the Kondo semi-conductor YbB12 has been measured over wide rangesof temperature (T = 8–690 K) and photon energy (hν ≥1.3 meV). The σ(ω) data reveal the entire crossover ofYbB12 from a metallic electronic structure at high T’s toa semiconducting one at low T’s. Associated with thegap development in σ(ω), a clear onset is newly foundat hν = 15 meV for T ≤ 20 K. The onset energy is

identified as the gap magnitude of YbB12 appearing inσ(ω). This gap in σ(ω) is interpreted as the indirect gap,which has been predicted by the renormalized-bandmodel of the Kondo semiconductor. On the other hand,the strong mid-infrared (mIR) peak observed in σ(ω) isinterpreted as arising from the direct gap. The absorp-tion coefficient around the onset and the mIR peakindeed show the characteristic energy dependencesexpected for indirect and direct optical transitions inconventional semiconductors.

IX-V-10 Kondo Ground States and Non-Fermi-Liquid Behavior in CeNi1–xCoxGe2

LEE, B. K.1; HONG, J. B.1; KIM, J. W.1; JANG, K.-H.1; MUN, E. D.1; JUNG, M. H.2; KIMURA, Shin-ichi; PARK, T.3; PARK, J. -G.1; KWON, Yong-seung1

(1Sungkyunkwan Univ., Korea; 2BKSI, Korea; 3LANL,U.S.A.)

[Phys. Rev. B 71, 214433 (9 pages) (2005)]

We report measurements of the magnetic suscep-tibility, specific heat, and electrical resistivity of theheavy fermion alloy series CeNi1–xCoxGe2. With in-creasing x, hybridization between the localized 4f andconduction band electrons is enhanced. The magneticorder observed at x = 0 is completely suppressed at x =0.3 and non-Fermi-liquid behavior appears at the criticalconcentration, which is analyzed in terms of two-dimen-sional antiferromagnetic quantum fluctuations. Specificheat and magnetic susceptibility data are quantitativelyexplained by the Coqblin-Schrieffer model with degen-erate impurity spin j = 1/2, 3/2, and 5/2 for Co concen-tration range of x ≤ 0.6, 0.7 ≤ x ≤ 0.8, and x ≥ 0.9,respectively.

IX-V-11 Infrared Spectroscopy underMultiextreme Conditions: Direct Observation ofPseudogap Formation and Collapse in CeSb

NISHI, Tatsuhiko1; KIMURA, Shin-ichi;TAKAHASHI, Toshiharu2; MORI, Yoshihisa3;KWON, Yong-seung4; IM, Hojun1; KITAZAWA,Hideaki5(1SOKENDAI; 2Kyoto Univ.; 3Okayama Univ. Sci.;4Sungkyunkwan Univ., Korea; 5NIMS)

[Phys. Rev. B 71, 220401(R) (4 pages) (2005)]

Infrared reflectivity measurements of CeSb undermultiextreme conditions (low temperatures, high pres-sures, and high magnetic fields) were performed. Apseudogap structure, which originates from the mag-netic band folding effect, responsible for the largeenhancement in the electrical resistivity in the single-layered antiferromagnetic structure (AF-1 phase) wasfound at a pressure of 4 GPa and at temperatures of35–50 K. The optical spectrum of the pseudogap chang-es to that of a metallic structure with increasing mag-netic field strength and increasing temperature. Thischange is the result of the magnetic phase transitionfrom the AF-1 phase to other phases as a function of the


magnetic field strength and temperature. This result isan important optical observation of the formation andcollapse of a pseudogap under multiextreme conditions.

IX-V-12 Infrared Study on CeSb under HighPressures

KIMURA, Shin-ichi; NISHI, Tatsuhiko1; MORI,Yoshihisa2; SUMIDA, Yukitsune2; TAKAHASHI,Toshiharu3; KWON, Yong-seung4; IM, Hojun1;KITAZAWA, Hideaki4(1SOKENDAI; 2Okayama Univ. Sci.; 3Kyoto Univ.;4Sungkyunkwan Univ., Korea; 5NIMS)

[Physica B 359-361, 190–192 (2005)]

The optical reflectivity spectra (R(ω)) of CeSb havebeen measured at high pressures to investigate the originof the physical properties appearing under pressures. At300 K, the pressure dependence of R(ω) revealed thatthe carrier density proportionally increases with increas-ing pressure up to 2.5 GPa. At lower temperature, theR(ω) spectrum drastically changes with both tempera-ture and pressure due to the complex magnetic phasediagram. Especially, at 2.5 GPa and 30 K, the R(ω)intensity below 0.2 eV decreases, on the contrary that ataround 0.3 eV increases. This result suggests that thedensity of states near the Fermi level decreases andshifts to the high-energy side.

IX-V-13 Electronic Structure of Bulk MetallicGlass Zr55Al10Cu30Ni5

SODA, Kazuo1; SHIMBA, Kurando1; YAGI,Shinya1; KATO, Masahiko1; TAKEUCHI,Tsunehiro1; MIZUTANI, Uichiro1; ZHANG, T.2;HASEGARA, M.2; INOUE, Akihisa2; OTO,Takahiro; KIMURA, Shin-ichi(1Nagoya Univ.; 2Tohoku Univ.)

[J. Electron Spectrosc. Relat. Phenom. 144-147,585–587 (2005)]

The electronic structure of a bulk metallic glass Zr55Al10Cu30Ni5 has been studied by means of photo-electron spectroscopy in order to understand the originsof its large glass formation ability and unique mechani-cal properties from the microscopic point of view. Thevalence-band photoelectron spectra show three bandsascribed to the Zr 4d, Ni 3d, and Cu 3d states. A re-markable feature of these bands is the highly symmetricspectral shape with the high-binding energy and narrowwidth in comparison with the d bands of the crystallinetransition metals. This is attributed to the lack of thecrystalline periodicity in the metallic glass as well as thereduction in the neighbouring atoms to hybridize withthose transition metals. A high-resolution valence-bandspectrum also reveals the intensity reduction near theFermi level, which implies that the pseudo-gap in theelectronic structure may be one of the important factorsfor the glass formation.

IX-V-14 Carrier-Induced Infrared MagneticCircular Dichroism in the MagnetoresistivePyrochlore Tl2Mn2O7

OKAMURA, Hidekazu1; KORETSUNE, Toshihisa1;KIMURA, Shin-ichi; NANBA, Takao1; IMAI,Hideto2; SHIMAKAWA, Yuichi2; KUBO, Yoshimi2(1Kobe Univ.; 2NEC Corp.)

[J. Phys. Soc. Jpn. 74, 970–974 (2005)]

Infrared magnetic circular dichloism (MCD), orequivalently magneto-optical Kerr effect, has been mea-sured on the Tl2Mn2O7 pyrochlore, which is well knownfor exhibiting a large magnetoresistance around theCurie temperature TC ~ 120 K. A circularly polarized,infrared synchrotron radiation is used as the lightsource. A pronounced MCD signal is observed exactlyat the plasma edge of the reflectivity near and below TC.However, contrary to the conventional behavior ofMCD for ferromagnets, the observed MCD of Tl2Mn2O7grows with the applied magnetic field, and not scaledwith the internal magnetization. It is shown that theseresults can be basically understood in terms of a classi-cal magnetoplasma resonance. The absence of a mag-netization-scaled MCD indicates a weak spin-orbitcoupling of the carriers in Tl2Mn2O7. We discuss thepresent results in terms of the microscopic electronicstructures of Tl2Mn2O7.

IX-V-15 Magnetic Ordering in FrustratedCe5Ni2Si3

LEE, B. K.1; RYU, D. H.1; KIM, D. Y.1; HONG, J.B.1; JUNG, M. H.2; KITAZAWA, Hideaki3;SUZUKI, Osamu3; KIMURA, Shin-ichi; KWON,Yong-seung1

(1Sungkyunkwan Univ., Korea; 2BKSI, Korea; 3NIMS)

[Phys. Rev. B 70, 224409 (5 pages) (2004)]

The transport, magnetic, and thermal properties arestudied on an antiferromagnetic compound Ce5Ni2Si3with TN = 7.3 K. We find signatures of spin fluctuationin this geometrically frustrated magnet. The Curie-Weiss fit gives a large value of the paramagnetic Curietemperature, yielding a frustration parameter f = 8.4.The electronic specific heat coefficient γ = 300 mJ/Cemol K2 is strongly enhanced, leading to residual entropyat low temperatures. The spin fluctuation is suppressedas the magnetic field exceeds the metamagnetic tran-sition field Hm = 1 T, where the magnetoresistancedecreases steeply. The steady increase of magnetic sus-ceptibility below TN is likely to be associated with thepresence of paramagnetic Ce ions. For La5Ni2Si3, asuperconducting transition is observed at TC = 1.8 K.

IX-V-16 Features of Fluorescence Spectra ofPolyethylene Terephthalate Films

OUCHI, Isuke1; NAKAI, Ikuo2; ONO, Mitsumasa3;KIMURA, Shin-ichi(1Tokushima Bunri Univ.; 2Tottori Univ.; 3TeijinDuPont Films Japan Ltd.)

182 RESEARCH ACTIVITIES IX UVSOR Facility

[Jpn. J. Appl. Phys. 43, 8107–8114 (2004)]

Out of two species of fluorescence of polyethyleneterephthalate (PET), intrinsic fluorescence (I), whichwas caused by short-wavelength (< 320 nm) excitation,was dominant for very thin films (less than a fewmicrons), while, trap fluorescence (II), excited at longerwavelengths (>320 nm), was much more intense forthick films. This fact was confirmed, and explained byan elementary formula. Effects of polymerization cata-lysts onto the fluorescence spectra were found to beindirect; namely, peak positions of the fluorescencewere not affected by catalyst systems, while fluores-cence intensity was sensitive not only to catalyst sys-tems but also to minute differences in local surround-ings. Effects of catalyst systems on the weak absorptionbands at 338 nm and 354 nm were examined. Integratedexcitation spectra were resolved; therein, a hidden n →π* state was found. Most likely, this is related with theweak absorptions at 338 nm and 354 nm, which are themajor origins of fluorescence (II).

IX-V-17 Anomalous Magnetic Properties andNon-Fermi-Liquid Behavior in Single Crystalsof the Kondo Lattice CeNiGe2–xSix

KIM, D. Y.1; RYU, D. H.1; HONG, J. B.1; PARK, J.-G.1; KWON, Yong-seung1; JUNG, M. A.1; JUNG,M. H.2; TAKEDA, Naoya3; ISHIKAWA,Masakazu3; KIMURA, Shin-ichi(1Sungkyunkwan Univ., Korea; 2KBSI, Korea; 3Univ.Tokyo)

[J. Phys.: Condens. Matter 16, 8323–8334 (2004)]

We report on the magnetic susceptibility, specificheat and electrical resistivity of the heavy fermioncompounds CeNiGe2–xSix (0 ≤ x ≤ 1). Compounds withx < 1 show antiferromagnetic order, which with increas-ing x shifts toward lower temperature owing to in-creased exchange coupling between the localized 4fmagnetic moments and conduction electrons. Eventu-ally, the magnetic order almost becomes absent, for x =1. An anomaly observed in the specific heat is wellinterpreted by the Kondo model for a degenerate impu-rity spin J = 1/2 in the Coqblin–Schrieffer limit. Acoherence peak indicative of the formation of a Kondolattice is found in the electrical resistivity, whose fea-tures are consistent with the results for the specific heat.Interestingly, there is a significant deviation fromFermi-liquid behaviour at the critical concentration x =1. This deviation is attributed to a quantum phase transi-tion in a model with two-dimensional antiferromagneticfluctuations.

IX-V-18 Sub-Natural Linewidth Auger ElectronSpectroscopy of the 2s Hole Decay in HCl

ITO, Kenji; HIKOSAKA, Yasumasa; KANEYASU,Tatsuo; SHIGEMASA, Eiji

Auger-photoelectron coincidence spectroscopy, inwhich Auger electrons are measured in coincidencewith the corresponding photoelectrons, can be a power-

ful tool to elucidate the decay dynamics of the core-holestates followed by the productions of doubly chargedatomic and molecular ions. In our coincidence method,we measure threshold photoelectrons as photoelectronsto attain high detection efficiency. We have applied thecoincidence method to the 2s hole decay in HCl. Wetuned photon energy at the Cl 2s ionization threshold ofHCl, and recorded the Auger electron spectrum incoincidence with the threshold photoelectrons. We haveobserved the Auger lines associated with the formationsof HCl++[(Cl 2p)–1(V)–1] states via the L1L2,3V Coster-Kronig transitions, which are much faster than otherAuger decay processes such as the LVV transitions.Ordinary Auger spectrum measured without any coinci-dences shows only broad structures due to the widenatural linewidth of the 2s hole states (1.8 eV FWHM).In contrast, several peaks appear on the coincidencespectrum we obtained, thanks to the sub-natural line-width regime which is achieved by the coincidenceobservation using the high resolution spectrometers.


IX-W-1 Growth and Scintillation Properties ofYb Doped Aluminate, Vanadate and SilicateSingle Crystals

YOSHIKAWA, Akira1; OGINO, Hiraku1; SHIM,Jan Bo1; KOCHURIKIN, V. V.2; NIKL, M.3;SOLOVIEVA, N.3; ONO, Shingo; SARUKURA,Nobuhiko; KIKUCHI, M.4; FUKUDA, Tsuguo1

(1Tohoku Univ.; 2GPI; 3Inst. Phys. AS CR; 4TohokuFukushi Univ.)

[Opt. Mater. 26, 529 (2004)]

For the purpose of quick screening for charge trans-fer (CT) transitions of Yb3 in various hosts, (Lu1–xYbx)3Al5O12 (Yb:LuAG) with x = 0.05, 0.15, 0.30 and(Y1–xYbx)AlO3 (Yb:YAP) with x = 0.05, 0.10, 0.30were grown by the micro-pulling-down method. (Y,Yb)VO4 with strong wetting was grown by edge definedfilm-fed growth method and materials, which requiremoderate temperature gradient, such as Ca8(La,Yb)2(PO4)6O2 and (Gd,Yb)2SiO5 were grown by Czochralskimethod. Strong dependence of the CT luminescencedecay time and intensity on temperature was observedfor Yb-doped LuAG and YAP. Super fast decay with0.85 ns decay time was observed in Yb(30%) dopedYAP at room temperature. Though the emission inten-sity is weak at room temperature, it exceeds severaltimes that of PbWO4. In addition, CT luminescence ofYb:YAP occurs at longer wavelength than in BaF2,which enables the usage of glass-based photomultiplierfor the detection. In addition, higher stopping powerwill be expected due to the higher density host com-pared with BaF2.

IX-W-2 Onset Detection of Solid-State PhaseTransition in Estrogen-Like Chemical viaTerahertz Transmission Spectroscopy

QUEMA, Alex; GOTO, Masahiro; SAKAI,Masahiro; JANAIRO, Gerardo1; OUENZERFI,Riadh; TAKAHASHI, Hiroshi; ONO, Shingo;SARUKURA, Nobuhiko(1De La Salle Univ.)

[Appl. Phys. Lett. 85, 3914 (2004)]

Solid-state phase transition onset in an endocrine-disrupting estrogen-like chemical (1,4-naphthol) isdetected using terahertz transmission spectroscopy. Theappearance of two absorption peaks and the sudden

upsurge of terahertz-radiation power at 210 K indicatethe onset of the solid-state phase transition. Differentialscanning microscopy reveals a first-order phase transi-tion at around 240 K while temperature-dependent x-raydiffraction analysis shows the occurrence of such phe-nomenon also at around 240 K. This demonstrates thesensitivity of the terahertz spectroscopic technique tophase transition since it provides a signal before suchphenomenon actually occurs.

IX-W-3 Design Principle of Wide-Gap FluorideHetero-Structures for Deep Ultraviolet OpticalDevices

OUENZERFI, Riadh; ONO, Shingo; QUEMA, Alex;GOTO, Masahiro; SAKAI, Masahiro; SARUKURA,Nobuhiko; NISHIMATSU, Takeshi1; TERAKUBO,Noriaki1; MIZUSEKI, Hiroshi1; KAWAZOE,Yoshiyuki1; SATO, Hiroki1; YOSHIKAWA, Akira1;FUKUDA, Tsuguo1

(1Tohoku Univ.)

[J. Appl. Phys. 96, 7655 (2004)]

The design of fluoride-based optical devices for deepultraviolet applications is discussed. Variations in theband-gap energy and band structure with respect tocomposition are investigated for Li(1–x)KxBa(1–y)MgyF3perovskites. The band-gap energy, lattice constant, andband structure of perovskitelike fluorides are estimatedbased on ab initio calculations within the local-densityapproximation. The lattice-matched double hetero-structure with direct band-gap compounds (Li(1–x)KxBa(1–y)MgyF3 on either LiBaF3 or KMgF3 substrates) ispromising for fabrication.

IX-W-4 Terahertz Time-Domain Spectroscopyof Amino Acids and Polypeptides

YAMAMOTO, Koji1; TOMINAGA, Keisuke1;SASAKAWA, Hiroaki1; TAMURA, Atsuo1;MURAKAMI, Hidetoshi; OHTAKE, Hideyuki;SARUKURA, Nobuhiko(1Kobe Univ.)

[Biophys. J. L22 (2005)]

Frequency-dependent absorption coefficients andrefractive indices of amino acids (glycine and L-alanine) and polypeptides (polyglycine and poly-L-alanine) in the wavenumber region from 7 to 55 cm–1

184 RESEARCH ACTIVITIES IX Laser Research Center for Molecular Science

Laser Research Center for Molecular Science

IX-W Developments and Researches of New Laser Materials

Although development of lasers is remarkable, there are no lasers which lase in ultraviolet and far infraredregions. However, it is expected that these kinds of lasers break out a great revolution in not only the molecularscience but also in the industrial world.

In this project we research characters of new materials for ultraviolet and far infrared lasers, and develop newlasers by using these laser materials.

were measured by terahertz timedomain spectroscopy.A vibrational band was observed at 45.5 cm–1 for poly-glycine, which was assigned as an interchain mode. Thereduced absorption cross sections of the amino acidsand polypeptides show power-law behavior. The expo-nents are different between the monomers and poly-mers, and those of the two polypeptides suggest that thetime dependences of the total dipole moments aresimilar in the timescale of subpico- to picoseconds.


IX-X-1 Spectroscopic Properties of Yb:GdVO4Single Crystal: Stark Levels, Selection Rules,and Polarized Cross Sections

SATO, Yoichi; TAIRA, Takunori; NAKAMURA,Osamu1; FURUKAWA, Yasunori1(1OXIDE)

[OSA Topical Meeting of Advanced Solid StatePhotonics MF8 (2005)]

Spectroscopic properties Yb:GdVO4 single crystalswere investigated. We determined the stark levels anddiscussed about the selection rules. We found that the1030.7-nm transition from the lowest level in uppermanifold to the highest level in lower manifold was for-bidden transition in π-polarization. The absorption crosssection, stimulated emission cross section, and radiativelifetime were also evaluated. σab and σem at 948-nmwere 6.1 and 6.7 × 10–20-cm2, respectively. The calcu-lated radiative lifetime of Yb:GdVO4 was 313-µs, andwas consistent to the reported fluorescence lifetime of320-µs. From the wave-profiles of σem and polarizeddecay rate, the averaged wavelength of fluorescence wasestimated to be 991-nm. If the pumping wavelength isset to 1000-nm, the absorption coefficient of 15 at.%Yb:GdVO4 is still 9.8-cm–1, and laser cooling effectshould be observed. Obtained spectroscopic parametersin this work were consistent with the previous report oflaser oscillation. Authors also indicate that Yb:GdVO4has enough absorption at pumping wavelength for lasercooling.

Figure 1. Polarized absorption and stimulated emission crosssections of Yb:GdVO4.

IX-X-2 Spectroscopic Properties of All-CeramicComposite with Layer-by-Layer of Nd:Y3Al5O12and Nd:Y3ScAl4O12

SATO, Yoichi; TAIRA, Takunori; IKESUE, Akio1

(1JFCC)

[Conf. Lasers Electro-Optics JTuC28 (2005)]

The ceramic laser materials have been greatly inter-ested because of their possibility for advanced lasers.The technique of composite ceramics has been especial-ly considered to be the most important in the ceramics.Recently, this new ceramics technology about compos-ite ceramics has been realized. In this work, we fabri-cated the all-ceramic composite with layer-by-layer ofNd:Y3ScAl4O12 (YSAG) and Nd:Y3Al5O12 (YAG).

The wide emission bandwidth of 5.5 nm in Nd:YSAG is composed of three transitions (R1-Y1, R1-Y2,R2-Y3), and contains the valley in its profile. The ratio ofpeak-to-valley is almost 50%, which reaches 93% inNd:YAG. Fortunately, the valley in the emission bandof Nd:YSAG overlaps the peak in the emission band ofNd:YAG. When we pumped from YSAG side with809.0 nm pumping source, this peak-to-valley improvedto 43%. If we fabricate the three-layered composite ofYAG, YSAG, and Y3Sc2Al3O12, this specimen will per-form more flat emission band. These profiles of fluores-cence in Figure 1 are related to the effective emissioncross-section, thus we can design the gain profile of thislayered composite material. Even in the case of diode-pumping, we can control the spectroscopic properties bytuning the temperature of laser diode.

As a result, we found that the tuning of the pumpingwavelength made the spectral profile of fluorescencefrom the composite ceramics more even than that fromsingle-layered Nd:Y3ScxAl5–xO12 ceramics. The tech-nique of composite ceramics is proved to be usefulbecause it can provide not only the compositional tuningbut also a new controllability by the selection of thepump source.


IX-X Development and Research of Advanced Tunable SolidState Lasers

Diode-pumped solid-state lasers can provide excellent spatial mode quality and narrow linewidths. The highspectral power brightness of these lasers has allowed high efficiency frequency extension by nonlinear frequencyconversion. Moreover, the availability of new and improved nonlinear optical crystals makes these techniques morepractical. Additionally, quasi phase matching (QPM) is a new technique instead of conventional birefringent phasematching for compensating phase velocity dispersion in frequency conversion. These kinds of advanced tunablesolid-state light sources, so to speak “Chroma Chip Lasers,” will assist the research of molecular science.

In this projects we are developing Chroma Chip Lasers based on diode-pumped-microchip-solid-sate lasers andadvanced nonlinear frequency conversion technique.

Figure 1. Fluorescence profiles of 1.0at.% Nd:YAG, Nd:YSAG, and their composite.

IX-X-3 Hybrid Process for Measurement ofSpectroscopic Properties of Nd:GdVO4

SATO, Yoichi; TAIRA, Takunori

[Pac. Rim Conf. Lasers Electro-Optics CWI2-5 (2005)]

In order to construct highly performing solid-statelasers, laser materials should be able to absorb effi-ciently the pump radiation. The request of high pumpabsorption efficiency is more important for the case inmicrochip laser scheme, or under direct pumping intothe emitting levels. Rare-earth doped vanadate crystalsare the promised candidates solid-state lasers with high-performance because of their desirable properties ofhigh optical absorption. However, there are many re-ports for an absorption cross section of the transitionbetween 4I9/2 and 4F5/2 in Nd:GdVO4. In this paper,authors discussed how to evaluate the spectroscopicproperties of Nd- and Yb-doped GdVO4 crystals.

We propose the “Hybrid Process” which is shown inFigure 1 as a technique for the spectroscopic evaluationin order to avoid overlooking the influences of emissionin absorption and the influences of absorption in emis-sion by simultaneous evaluation. This process also givesthe radiative quantum efficiency (ηr). We studied Nd:GdVO4 (Shandong Newphotonics) and Nd:YVO4 (ITI)according to the Hybrid Process.

As a result, rare-earth doped vanadate crystals arethe promised candidates solid-state lasers due to theirlarge cross sections and relatively high thermal conduc-tivity. In order to perform these superior characteristics,we have to notice that heavy heat generation under non-lasing condition and the difference in the thermal con-ductivity depending on the crystal-axis.

Figure 1. The flow-chart of “Hybrid Process” for measure-ment of the spectroscopic properties in Nd:vanadate.

IV-X-4 Absorption, Emission SpectrumProperties and Efficient Laser Performances ofYb:Y3ScAl4O12 Ceramics

SAIKAWA, Jiro; SATO, Yoichi; TAIRA, Takunori;IKESUE, Akio1

(1JFCC)

[Appl. Phys. Lett. 85, 1898 (2004)]

We report on the continuous-wave laser perfor-mances of Yb3+-doped disordered Y3Al5O12/Y3Sc2Al4O12 (YAG/YSAG) ceramics fabricated by sinteringmethod. These new materials exhibit relatively lowminimum pump intensity (Imin) and broad emissionbandwidth even in the yttrium aluminum garnet sys-tems. The value of Imin in the Yb:Y3ScAl4O12 ceramicswas found to be 2/3 compared with the Yb:YAG singlecrystal under 970-nm zero-line pumping. Efficient laseroscillation of 72% slope efficiency was obtained forinput pump power. These materials attract great interestfor high power femtosecond microchip lasers and am-plifier applications.

IX-X-5 Passive Mode Locking of a MixedGarnet Yb:Y3ScAl4O12 Ceramic Laser

SAIKAWA, Jiro; SATO, Yoichi; TAIRA, Takunori;IKESUE, Akio1

(1JFCC)

[Appl. Phys. Lett. 85, 5845 (2004)]

We have demonstrated a passively mode-lockedYb3+-doped Y3ScAl4O12 ceramic laser, which is a solidsolution of Y3Al5O12 (YAG) and Y3Sc2Al3O12 (YSAG), by using a semiconductor saturable-absorber mir-ror (SESAM). The maximum average output power wasas high as 150 mW with a pulse duration of 500 fs. Witha 0.5% output coupler, pulses as short as 280 fs havingan average output power of 62 mW at 1035.8 nm wereobtained.

IX-X-6 High-Power Operation of Diode Edge-Pumped, Glue-Bonded, Composite Yb:Y3Al5O12Microchip Laser with Ceramic, Undoped YAGPump Light-Guide

TSUNEKANE, Masaki; TAIRA, Takunori

[Jpn. J. Appl. Phys. in press]

The high-power operation of a diode edge-pumped,composite Yb3+-doped Y3Al5O12 (Yb:YAG) microchiplaser has been demonstrated. The novel compositemicrochip has a 5-mm-diameter, 300-µm-thickness,single-crystal Yb:YAG core and a transparent ceramic,undoped YAG pump light-guide surrounding the corewith the same thickness. The high-reflection coated faceof the microchip was bonded to a water-cooled heat-sink by a thermally conductive glue for efficient con-


ductive cooling. The pump light from a fourfold diodestack directly coupled to the light-guide and maximumoutput powers of 410 W (peak) and 285 W have beensuccessfully obtained at an input pump power of 866 Win quasi-continuous-wave (10 ms, 10 Hz) and continu-ous-wave operations, respectively, at room temperature.

Figure 1. Input pump power versus laser output power ofdiode edge-pumped, composite Yb:YAG microchip laser inQCW and CW operations at room temperature.

IX-X-7 Continuous-Wave Deep Blue Generationin a Periodically Poled MgO:LiNbO3 Crystal bySingle-Pass Frequency Doubling of a 912-nmNd:GdVO4 Laser

MIZUUCHI, Kiminori1; MORIKAWA, Akihiro1;SUGITA, Tomoya1; YAMAMOTO, Kazuhisa1;PAVEL, Nicolaie2; TAIRA, Takunori(1Matsushita Co., Ltd.; 2IAP-NILPRP, Romania)

[Jpn. J. Appl. Phys. 43, L1293 (2004)]

We report blue emission at 456 nm by single-passsecond-harmonic generation in a bulk periodically-poled MgO:LiNbO3 crystal, for the first time to our bestknowledge. Using as a pumping source a continuous-wave Nd:GdVO4 laser operating at 912 nm, blue powerof 167 mW with 8.3% infrared-to-blue conversion effi-ciency and 4.2%/W normalized conversion efficiencywas obtained. The present data, combined with our pre-vious results on green generation, supports the prospectof obtaining compact and high power visible sourcesbased on bulk periodically poled MgO:LiNbO3.

IX-X-8 Continuous-Wave Ultraviolet Generationat 354-nm in a Periodically Poled MgO:LiNbO3by Frequency Tripling of a Diode End-PumpedNd:GdVO4 Microlaser

MIZUUCHI, Kiminori1; MORIKAWA, Akihiro1;SUGITA, Tomoya1; YAMAMOTO, Kazuhisa1;PAVEL, Nicolaie2; TAIRA, Takunori(1Matsushita Co., Ltd.; 2IAP-NILPRP, Romania)

[Appl. Phys. Lett. 85, 3959 (2004)]

Irregular side spread of polarization inversion wassuppressed in PPMgLN up to 2-mm thickness by usinga multipulse poling method. Cascaded THG was per-formed by employing a first-order SHG-QPM PPMgLNfollowed by a SFG-QPM PPMgLN stage, and a 1063nm Nd:GdVO4 laser as a pumping source. CW power of47 mW at 354 nm with 3.9%/W/cm normalized conver-sion efficiency was obtained. To our knowledge this isthe first demonstration in PPMgLN of such a systemand the highest UV power at 354 nm reported by CWsingle-pass process in a QPM structure. The presentresult supports the prospect of obtaining compact andhigh power UV source based on bulk periodically poledMgO:LiNbO3.

IX-X-9 High-Power Continuous-WaveIntracavity Frequency-Doubled Nd:GdVO4-LBOLaser under Diode Pumping into the EmittingLevel

PAVEL, Nicolaie1; TAIRA, Takunori(1IAP-NILPRP, Romania)

[IEEE J. Sel. Top. Quantum Electron. 11, 631 (2005)]

Continuous-wave emission in Nd:GdVO4 at the 1-µm fundamental wavelength and 531-nm second har-monic, which was obtained by intracavity frequency-doubling with LBO, is investigated under end-pumpingwith high-power diode laser at 808 and 879 nm. Themaximum green power of 5.1 W with 0.31 overalloptical-to-optical efficiency in a beam of M2 = 1.46 wasobtained under 879-nm pumping, directly into the 4F3/2emitting level. To the authors best knowledge this is thehighest CW green power obtained for the Nd:GdVO4laser material.

IX-X-10 Deep Blue Generation at 456 nm in aPeriodically Poled MgO:LiNbO3 Ridge-TypeWaveguide by Single-Pass Frequency Doublingof a Nd:GdVO4 Micro-Laser

PAVEL, Nicolaie1; TAIRA, Takunori; IWAI,Makato2; YOSHINO, Takeshi2; IMAEDA, Minoru2

(1IAP-NILPRP, Romania; 2NGK)

[Conf. Lasers Electro-Optics CTuC30 (2005)]

This paper reports on our work toward scaling deepblue light by SHG-QPM process in a PPMgLN ridge-type waveguide: 93 mW power at 456 nm was achievedby single-pass SHG of a 912-nm Nd:GdVO4 laser.

IX-X-11 Efficient 1.06 and 1.34-µm LaserEmission of Highly-Doped Nd:YAG under 885-nm Diode Pumping into the Emitting Level


[European Conf. Lasers Electro-Optics CA-19-MON(2005)]


This work reports on 1.34-µm emission in Nd:YAGunder direct pumping into the emitting level, at 885 nm,the first demonstration of such a system to the best ofour knowledge. CW output power of 3.8 W at 1.34 µmwith overall optical-to-optical efficiency of 0.26 is ob-tained from a 2.5-at.% Nd:YAG single crystal pumpedinto the 4F3/2 level with a high-brightness 885-nm diodelaser. The influence of the lasing wavelength andmedium concentration on the thermal effects induced byoptical pumping into the active component is discussed.It is shown that laser emission at 1.3 µm increases thethermal effects in medium only under a certain value ofCNd. This behavior was checked be mapping the tem-perature of the output surface of the Nd:YAG crystals.These results demonstrate that diode laser pumping intothe emitting level of concentrated Nd-based laser ma-terials is a solution for construction of efficient micro-lasers and for scaling to high power.

IX-X-12 High-Power Multi-Pass PumpedMicrochip Nd:GdVO4 Laser


[Pacific Rim Conf. Lasers Electro-Optics CTuI3-5(2005)]

We describe a continuous-wave thin-disk Nd:GdVO4 laser in a multi-pass pumping scheme. Employinga 250-µm thick, 0.5-at.% Nd:GdVO4 crystal, a maxi-mum output power of 13.9 W was obtained for 22 Wabsorbed power; the slope efficiency in absorbed powerwas 0.65. Pumping at 879 nm, directly into the 4F3/2emitting level, resulted in laser operation with slopeefficiency in absorbed power of 0.69; the laser outputpower was 3.6 W at an absorbed pump power of 6.2 W.We appreciate that with an improved heat transferbetween the Nd:GdVO4 and the cooling system, a Nd:GdVO4 medium of lower doping and an increasednumber of passes of the pump radiation, this geometrycould be also a good solution for efficient laser emissionat 912 nm.

IX-X-13 Highly Efficient New PumpingConfiguration for Microchip Solid State Laser

DASCALU, Traian1; TAIRA, Takunori(1IAP-NILPRP, Romania)

[European Conf. Lasers Electro-Optics CThu4-2(2005)]

We propose a new pumping scheme which allows94% absorption efficiency in Yb:YAG 15 at.% with 200µm thickness with uniform pump distribution. This con-figuration can be scaled up and it is very attractiveespecially for high power quasi-4-levels lasers wherethe reabsorption losses are important.

IX-X-14 High Energy Quasi-Phase-MatchedOptical Parametric Oscillation in a 3-mm-ThickPeriodically Poled MgO:LiNbO3 Device

ISHIZUKI, Hideki; SHOJI, Ichiro; TAIRA,Takunori

[Opt. Lett. 29, 2527 (2004)]

We presented high energy optical parametric oscilla-tion (OPO) using 3-mm-thcik periodically poled MgO:LN (PPMgLN) device. The maximum total outputenergy of 22 mJ at the pump energy of 46 mJ wasobtained using a Q-switched Nd:YAG laser of 30 Hzrepetition rate with 15 ns pulse duration. The large-aperture PPMgLN devices would enable us to realizehigh-energy wavelength conversion, short pulse amplifi-cation, and pulse compression.


IX-Y-1 Development of a High-Precision SlitBlade for the Transmission-GratingSpectrometer

KONDO, Takuhiko; SUZUI, Mitsukazu; TORII,Tatsuharu1; MASUDA, Tadashi1; HORIGOME,Toshio; HATSUI, Takaki(1Nagoya Univ.)

Development of the transmission-grating spectrom-eter for soft X-ray emission spectroscopy has been car-ried out by the Department Vacuum UV Photoscience.

In order to improve further the energy resolution ofthe spectrometer, an entrance slit with the minimum slitopening of 1mm has been developed. In order to main-tain the spectrometer efficiency, the distance betweenthe sample and the slit is designed to be less than 1 mm.Accordingly, the slit blades are to be smaller than 13 ×10 × 2.5 mm3. These requirements demanded a develop-ment of slit blades with a roughness of less than 0.3 µmusing a high-precision polishing process.

The blades were polished first on the side A and B(Figure 1). The resulting roughness was less than Ra 7nm. The edge surfaces were polished by using a clampas shown in Figure 2. The four blades were pressed bythe two plates via two screws (M4) so as to minimizethe gap between the blades. The pressure was optimizedso that the pile up did not occur during the polishingprocess. The resulting slit blade is shown in Figure 3.Figure 4 is the top view of the slit blade from A side.The edge roughness was about 0.3 µm.

Figure 1. Schematic view of the slit blade.

Figure 2. The clamp for the polishing of the edge surfaces.

Figure 3. Photograph of the slit.

Figure 4. Top view of the slit blade observed by SEM.

190 RESEARCH ACTIVITIES IX Equipment Development Center

Equipment Development Center

IX-Y Development of New Instruments and ExperimentalDevices

The technical staff of the Equipment Development Center is partly engaged in planning, researching, designingand constructing high technology experimental instruments in collaboration with the scientific staff. And theseexperimental instruments are incorporated with new manufacturing technology and new mechanical idea.

B sideA side

Screw

Plate

Slit blade

IX-Y-2 Manufacture of Glass MicroreactorChips

AOYAMA, Masaki; SUZUI, Mitsukazu;FUKUYAMA, Naoshi; YAMADA, Yoichi M. A.;UOZUMI, Yasuhiro

Glass microreactor chips used for catalyst researchin Research Center for Molecular-scale Nanosciencewere manufactured.

Although glass chips are usually manufactured byphotolithography and wet etching, it takes expense andtime to manufacture many arbitrary flow patterns. Then,we attached the diamond grinding tool in the generalmachine tool, and processed flow patterns into it.

The SEM photograph of flow patterns of a chip isshown in Figure 1. The quality of the material wasPYREX glass, and the slot width and depth were 100µm and 40 µm, respectively. Although generating of thedeficit of a detailed crack and edge could become aproblem in processing of a brittle material, it wasprocessed by spindle speed 50,000 rpm, feed rate 1.0mm/min, the depth of cut 5 µm, and diamond toolparticle size #1000, and good flow patterns whoseprocessing side coarseness were about 1.5 µm wereobtained.

Such processing technology is applied to processingof brittle material such as silicone in addition to glass,and is useful also to manufacture of the micro parts forDepartment of Vacuum UV Photoscience.

Figure 1. Flow patterns of a chip.

IX-Y-3 Micro Processing by a Femto-SecondLaser

AOYAMA, Masaki; YANO, Takayuki; SUZUI,Mitsukazu; SASAKI, Ryuichiro1; NAGAI,Hiroyuki1; YOSHIDA, Makoto1; TAKAHASHI,Kazuyuki; KOBAYASHI, Hayao; RAHMAN, Md.Mashiur; URISU, Tsuneo(1AISHIN Seiki Co., Ltd.)

Micro fabrication processing was done by using thefemto-second fiber laser (FCPAµJewel B-250) manu-factured by IMRA in laboratory of AISHIN Seiki Co.,Ltd.

Processing conditions are center wavelength 1560nm, pulse width 900 fs, and repetition frequency 256

kHz. The main two cases are described in the following.Diamond Anvil Cell for the high pressure experi-

ment will be used by Department of Molecular Assem-blies. In order to draw four probes out of the samplecavity of Diamond Anvil Cell, the groove for the wiringon the metal gasket of Diamond Anvil Cell is necessary.Schematic view of the metal gasket for the high pres-sure experiment is shown in Figure 1. The hole is at thecenter of gasket plate (8 × 8 × 0.3 mm3 Inconel 625) anda diameter of 0.4 mm. Prepressing between both sidesof the plate by Diamond Anvil resulted in the basin-likeplastic deformation of the whole plate and a height ofabout 20 µm of the swelling around the central hole. Inorder to pass through the wiring with a diameter of 10µm, the required groove width and depth are consideredto be about 50 µm and 30 µm, respectively.

Excellent groove processing was attained in a shortterm with no heat effect on the sharpness of the edgeand no deposition by melting. This result is shown inFigure 2.

It was applied to hole processing for the biosensordevice used in Department of Vacuum UV Photo-science. An AFM measurement after hole processing isshown in Figure 3. Drilling of the Cobalt layer on SiO2with a diameter of about 1.5 µm could be achieved byadjusting laser power and an exposure time.

A trial of the partial removal of a gold thin film froma circuit pattern on the SiO2-covered silicon substrate bythe femto-second laser is now in progress.

Figure 1. Schematic view of the metal gasket.

Figure 2.


Figure 3. The measurement result of the cross section profileof a hole.

IX-Y-4 Development of Electrical ControlSystem of Fluorescence Recovery afterPhotobleaching Apparatus UsingSemiconductor Laser for Illumination

YOSHIDA, Hisashi; URISU, Tsuneo

We have developed the electrical control system ofthe fluorescence recovery after photobleaching (FRAP)apparatus as schematically shown in Figure 1. Tworecording devices are equipped in the setup. One is acharge coupled device (CCD) by which the samplesurface image and the photobleached spot image aremonitored. The other one is photo-multiplier (PMT) bywhich the time dependence of the fluorescence intensityat the photobleaching spot can be monitored. A pinholewith 100 µm diameter is set at the confocal point of themicroscope before the PMT. Two neutral density filterswith different transmission coefficients are inserted tothe filter holder to attenuate the UV lamp and laserintensities, respectively. The UV lamp illumination wasused mainly for sample setting and was turned offduring the photobleaching and the fluorescence recoveryprocess. The photo-multiplier recording, which givesthe time dependence of the fluorescence recovery direct-ly, is very convenient in the calculation of the diffusionconstant. The block diagram of a laser driving and thephoto-multiplier detection system is shown in Figure 2.The semiconductor laser is drove by the bleaching pulseand succeeding pulse train of the sampling pulse.

The drive voltage 1.25 V correspond to the secondharmonic output of ~5 mW. The fluoresecence recoverycan be monitored by the weak sampling pulse trainwithout giving damage to dye molecules. The relationbetween the laser driving pulses and the photo-multipli-er output monitoring pulse are shown also in Figure 2.

Figure 1.

Figure 2.

192 RESEARCH ACTIVITIES IX Equipment Development Center

IX-Z-1 Molecular Arrangement in theCocrystals of 1,1',3,3'-Tetramethyl-2,2'-bi-1H-imidazolium Bis(tetraphenylborate) withKetone, Aldehyde, and Nitrile as GuestMolecules

ONO, Katsuhiko1; IWAO, Takeshi1; UCHIUMI,Hideki1; SUZUKI, Takahisa1; TOMURA, Masaaki;OHKITA, Masakazu1; SAITO, Katsuhiro1

(1Nagoya Inst. Tech.)

[Bull. Chem. Soc. Jpn. 78, 867–872 (2005)]

1,1’,3,3’-Tetramethyl-2,2’-bi-1H-imidazoliumbis(tetraphenylborate), an ion-association compound,afforded inclusion crystals with a variety of guestmolecules, such as ketone, aldehyde, and nitrile. X-raycrystallographic analyses revealed intermolecularinteractions between the biimidazolium dication and theguest molecules in the inclusion crystals. Their contactmodes depended on the molecular structures of the guestmolecules, resulting in various molecular arrangements.

IX-Z-2 Macrocyclic and Acyclic Bis(2,5-diphenyl-1,3,4-oxadiazole)s with Electron-Transporting and Hole-Blocking Ability inOrganic Electroluminescent Devices

ONO, Katsuhiko1; EZAKA, Seiichi1;HIGASHIBATA, Akinori1; HOSOKAWA, Ryohei1;OHKITA, Masakazu1; SAITO, Katsuhiro1; SUTO,Michitaka2; TOMURA, Masaaki; MATSUSHITA,Yosuke3; NAKA, Shigeki3; OKADA, Hiroyuki3;ONNAGAWA, Hiroyoshi3(1Nagoya Inst. Tech.; 2Dow Corning Asia Ltd.;3Toyama Univ.)

[Macromol. Chem. Phys. 206, 1576–1582 (2005)]

Two types of bis(2,5-diphenyl-1,3,4-oxadiazole)s,macrocyclic and acyclic, were prepared and evaluatedas electron-transporting and hole-blocking materials in

phosphorescent EL devices. Maximum efficiencies ofηext = 10.4% at J = 0.11 mA·cm–2 for the macrocycleand ηext = 14.1% at J = 3.01 mA·cm–2 for the acyclewere observed. X-ray crystallographic analysis andDSC measurements revealed a strong intermolecularinteraction between the macrocycles and weaker inter-molecular interactions between the acycles. The EL char-acteristics depend on the intermolecular interactions.

IX-Z-3 Synthesis, Characterization and FETProperties of Novel DithazolylbenzothiadiazoleDerivatives

AKHTARUZZAMAN, Md.1; KAMATA, Naoto1;NISHIDA, Jun-ichi1; ANDO, Shinji1; TADA,Hirokazu2; TOMURA, Masaaki; YAMASHITA,Yoshiro3

(1Tokyo Inst. Tech.; 2IMS and Osaka Univ.; 3IMS andTokyo Inst. Tech.)

[Chem. Commun. 3183–3185 (2005)]

Novel dithiazolylbenzothiadiazole derivatives easilyobtained show efficient fluorescence with high electronaffinity. The FET device of a trifluoromethylphenylderivative exhibited a good n-type performance withhigh electron mobility. Since substituents can be easilyintroduced to the α-position of thiazole, the dithiazolyl-benzothiadiazole unit would be useful as a core forunique electron-accepting π-conjugated molecules.


Safety Office

IX-Z Development of Novel Heterocyclic Compounds andTheir Molecular Assemblies for Advanced Materials

Heterocycles containing sulfur and/or nitrogen atoms are useful as components of functional materials sinceheteroatoms in their rings are helpful to stabilize ions or ion-radical species, and extended π-conjugation decreasesCoulombic repulsion. In addition intermolecular interactions caused by heteroatom contacts can be expected to formnovel molecular assemblies. In this project new electron acceptors, donors, and donor-acceptor compounds based onheterocycles such as 1,2,5-thiadiazole and 1,3-dithiole were synthesized and their properties including those of thecharge-transfer complexes or ion-radical salts were investigated. Unique crystal structures were constructed by usingweak intermolecular interactions such as hydrogen bonding or heteroatom contacts.

NMe

MeN

NMe

MeN

2 BPh4-

O

NN

N N

O

O

NN

N N

O

macrocycle acycle

NS

N

N

SS

N

RR

R = H BrN

S N

N CF3

research activities ix research center for molecular-scale

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