0018-1439/01/3502- $25.00 © 2001

MAIK “Nauka

/Interperiodica”0134

High Energy Chemistry, Vol. 35, No. 2, 2001, pp. 134–137. Translated from Khimiya Vysokikh Energii, Vol. 35, No. 2, 2001, pp. 157–160.Original Russian Text Copyright © 2001 by Pikaev.

The Pulse’2000 Sixth International Conference onPulse Studies in Chemistry, Biology, and Physics washeld on September 9–14, 2000 in Leba (Poland). Thepreceding conferences on this subject matter were heldin the following Polish cities: Lodz (1985), Czernie-jewo (1988), Pultusk (1991), Lodz and Zakopane(1994), and Szczyrk (1997).

Dr.

J. Gebicki

(Institute of Applied Radiation Chem-istry, Technical University, Lodz) was the chairpersonof the Organizing Committee. Approximately 100 spe-cialists from Belarus, Canada, Czech Republic, France,Germany, Hungary, India, Israel, Japan, the Nether-lands, Poland, Russia, Sweden, Switzerland, the UnitedKingdom, and the United States took part in the confer-ence.

The main topics of the conference included theapplications of pulse radiolysis to studies of primaryradiation-chemical processes in various systems (gases,water, aqueous solutions, organic liquids, and poly-mers); the kinetics of ultrafast reactions and relaxationdynamics; the formation of metal and semiconductorclusters; the nature of organic radical ions; some fea-tures of laser photolysis; and theoretical calculationsconcerning the track structure of ionizing particles, theelectron–ion recombination in liquids with high mobil-ity of primary species, and free-electron transfer innonpolar media. At 10 sessions, 36 invited and declaredoral papers were delivered and discussed. In addition,46 poster communications were presented. The texts ofall papers and communications will be published in thejournal

Research on Chemical Intermediates

in 2001.Reactions involving electrons in irradiated systems

were discussed in several lectures.

O. Brede

(Germany)summarized data obtained by his research team con-cerning the electron-transfer processes in nonpolarmedia. In particular, it was noted that uncorrelated freeradical cations participate in the reactions of free-elec-tron transfer in irradiated nonpolar liquids (hydrocar-bons and alkyl chlorides).

Y. Hatano

(Japan) presentedthe results of measurements and calculations of theelectron–ion recombination rate constant (

k

r

) and theelectron mobility (

µ

e

) in nonpolar systems (hydrocar-bons, tetramethylsilane, and inert gases at high pres-sures). Pulse radiolysis with the conductometric detec-tion of transient species was used for the measure-

ments. The effects of an external electric field, thedensity of the system, and the ionic charge on the val-ues of

k

r

and

µ

e

were examined. The data were com-pared to the results of calculations by the Debye theory.Deviations from this theory were found in systems withhigh electron mobilities (

µ

e

> 100 cm

2

V

–1

s

–1

).

S. Pim-blott et al.

(USA, UK) theoretically substantiated(using a stochastic model) the effect of the track struc-ture of ionizing particles on the kinetics of radiation-chemical reactions. Special attention was given to thereactions of the precursors of hydrated electrons andmolecular hydrogen. It was noted that the energy ofslowing-down electrons affects the rate of intratrackreactions.

M. Wojcik

(Poland) and

M. Tachiya

(Japan)calculated the rate constants of electron–ion recombi-nation in systems with high mobility of primary parti-cles. Two approximations were used. One of them is aone-parameter model of electron motion. The other ismore complicated; it treats electron trajectories andcross sections as energy-dependent. The one-electronreduction of disulfide bonds in proteins and modelcompounds was considered in a lecture by

Ch. Houee-Levin

and

J. Berges

(France). The reactivity of the thiylradicals of proteins, which are formed upon the ruptureof a disulfide bond as a result of an electron attack, wasstudied in detail. Kinetic isotope effects in the reactionsof hydrogen abstraction from formate ions by muo-nium, and H and D atoms in aqueous solutions were thesubject matter of a lecture by

E. Roduner

and cowork-ers (Germany). Pulse EPR and MuPR techniques wereused. A considerable effect of the substitution of D forH in the formate ion on the activation energies and pre-exponential factors was found.

A special session was devoted to the high-tempera-ture radiolysis of water. This is due to the design ofsupercritical water-cooled nuclear reactors.

D. Bartels

(USA) discussed the aspects of pulse radiolysis ofwater in relation to its phase diagram. Some reactionswere examined, and the yields of hydrated electronsnear the critical point were measured.

C. Stuwart

(Can-ada) performed kinetic and mechanistic studies of theradiolysis of liquid heavy water at temperatures up to

310°C

as applied to the conditions of a Canadian-design CANDU heavy-water reactor. The kinetics ofautoreactions of

D

and received primary consid-O2– O2

–

CHRONICLE

Pulse’2000 Sixth International Conference on Pulse Studiesin Chemistry, Biology, and Physics

A. K. Pikaev

Institute of Physical Chemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 117915 Russia

Received October 23, 2000

HIGH ENERGY CHEMISTRY

Vol. 35

No. 2

2001

PULSE’2000 SIXTH INTERNATIONAL CONFERENCE ON PULSE STUDIES 135

eration.

D. Swiatla-Wojcik

(Poland) and

G. Buxton

(UK) presented a lecture on the simulation of light andheavy water radiolysis at temperatures up to

300°C

using the diffusion kinetics theory. In particular, thetemperature dependence of the radiation-chemicalyields of primary species in

H

2

O

and

D

2

O

on radiolysisunder exposure to radiation with LET up to 90 eV/nmwas calculated.

Y. Katsumura

(Japan) presented theresults of a study on the pulse radiolysis of water athigh temperatures and under supercritical conditions.The optical absorption spectra of hydrated electronsand

C

and (

SCN

radical ions were measured attemperatures up to

500°C

and pressures up to 50 MPa.The absorption band maximums of hydrated electronswere detected at 720, 800, 940, 1030, 1050, and1080 nm at room temperature, 100, 200, 250, 300, and

400°C

, respectively. The positions of bands and theabsorption coefficients of the above radical ions alsostrongly depend on temperature.

The formation and properties of short-lived speciesin gases were considered in three lectures.

D. Arm-strong

and

A. Rauk

(Canada) summarized data on theeffect of cluster formation on the potential energy sur-face in electron + molecule reactions. It was found thatclustering in the radiolysis of gases (for example, RX)can significantly affect the threshold energy of appear-ance of ions in electron capture reactions. Data on thecross sections and rate coefficients of electron colli-sions in plasma-chemical reactions of

CF

4

, CHF

3

, C

2

F

6

,etc., were critically surveyed in a lecture by

L. Christo-phorou

and

J. Olthoff

(USA). A review of informationon elementary plasma-chemical reactions was given ina lecture by

E. Illenberger

(Germany). Electron colli-sion-induced ionization, electronic excitation, electronattachment, and ion recombination processes were con-sidered.

Two sessions were devoted to radical ions in organicmedia.

S. Tagawa

(Japan) described a new picosecondand subpicosecond pulse radiolysis facility, which wasdesigned at the Osaka University. Its operation is basedon the synchronization of a single picosecond electronpulse with a single femtosecond laser pulse. A resolu-tion of 800 fs was achieved. The first experimentalresults were obtained.

F. Williams

(USA) presented alecture on the rearrangements of organic moleculesupon ionization. It was concluded that the rearrange-ments of radical cations resulting from ionization cantake place with or without transferring a hydrogen atomor an alkyl group. Radical ions formed upon dissocia-tion were the subject matter of a lecture by

A. Marcineket al.

(Poland). The radical cations of benzopinacol, adimer of 10-methylacridine, and brominated psoralenin a rigid matrix were described. The formation andreactivity of enol ester radical cations in aqueous solu-tions were considered in a lecture by

K. Bernchard

and

S. Steenken

(Germany). These species were obtainedby photoionization or in the reactions of electron trans-fer to oxidizing radicals formed by radiolysis.

O3– )2

–

Biochemical problems were discussed in four lec-tures. Data on the oxidation reactions of amino acidswith radicals in an aqueous solution on pulse radiolysisand flash photolysis were considered in a lecture by

K.-D. Asmus et al.

(USA). Glycine, alanine,

α

-methy-lalanine, and

N,N

-dimethylglycine were examined.Data on intermediates, their yields, and the rate con-stants of reactions involving these intermediates werepresented.

K. Bobrowski

(Poland) summarized infor-mation (obtained in his laboratory) concerning oxida-tion reactions in oligopeptides containing methionine.Particular emphasis was placed upon the mechanism ofradiation-chemical or photochemical oxidation (by OHradicals) of oligopeptides with one or several methion-ine residues.

R. Flyint et al.

(USA, Germany) demon-strated in their lecture that the

CH

3

S(O)

radical wasformed in the reaction of methanesulfinic acid withOH. Moreover, the

γ

-radiolysis of oxygen- and

N

2

O

-saturated aqueous solutions of this acid was foundto involve a chain reaction of the formation of methane-sulfonic acid. A lecture by

Z. Abedinzadeh et al.

(France) was devoted to the reactivity of

N

-acetylcys-teine toward the radical ion. The rate constant of areaction between these substances was measured to beequal to 68 l mol

–1

s

–1

.Radiation polymerization was considered in three

lectures. The results of studies on the radiation-inducedand photochemical polymerization of some monomersvia a radical cation mechanism were presented in a lec-ture by

W. Knolle et al.

(Germany). For this purpose,the radical cations of vinyl monomers in frozen freonmatrices were obtained by electron-beam irradiation.The irradiated system thawed, and the reactions of rad-ical cations were monitored by EPR spectroscopy.

L. Luthjens et al.

(the Netherlands) delivered a lectureon studies of the radiation polymerization of methylmethacrylate in the continuous and pulse modes by flu-orescence analysis. The process was monitored by fol-lowing the fluorescence of special additives. The equi-librium radiation polymerization of methacrylic acid inan aqueous solution was discussed in a lecture by

P. Ulanski et al.

(Poland, Germany). The important roleof OH radicals played in the depolymerization ofpoly(methacrylic acid) was demonstrated.

Ultrafast reactions and relaxation dynamics werethe subject matter of five lectures.

J. Hynes

(Germany,USA) considered proton transfer in the reactions ofelectronically excited molecules in solution. Attentionwas focused on factors responsible for the value of acti-vation energy, the nature of elementary processes, andthe role of increased acidity as compared with the reac-tions of ground-state molecules. A lecture by

P. Reid

(USA) was devoted to the geminate recombination andvibrational relaxation of ClO

2

under photochemicalaction. Fast-response resonance Raman spectroscopywas used. In particular, data on the subpicosecond gem-inate recombination of ClO and O photofragmentswere presented.

V. Sundstroem

(Sweden) considered

O.

O2–

136

HIGH ENERGY CHEMISTRY

Vol. 35

No. 2

2001

PIKAEV

the reaction dynamics in biological and artificial pig-ment systems under exposure to light. Proteins, poly-mer films, and semiconductors were used as test mate-rials. The interaction of terawatt laser pulses with purewater was discussed in a lecture by

S. Pommeret et al.

(France). For example, the formation of hydrated elec-trons with a decimolar concentration was detected.

J. Waluk

(Poland) summarized information on sym-metrical and asymmetrical minimums in the photoin-duced reactions of double proton transfer. These reac-tions were investigated in the case of porphyrin isomersand alcoholic complexes of bifunctional chro-mophores. The minimums are symmetrical and asym-metrical in the former and latter systems, respectively.

Two lectures were concerned with the formation ofmetal and semiconductor clusters on radiolysis andlaser photolysis.

S. Kapoor

(India) presented a lectureon metal nanoparticles. The formation and properties ofcadmium, cobalt, nickel, silver, and copper nanoparti-cles were considered. Ultrashort laser pulses were usedfor studying the dynamics of this process. The use ofsemiconductor and metal clusters produced by ionizingradiation for the development of optical limiting sys-tems was the subject matter of a lecture by

M. Mostafavi

(France). The lecturer noted that goldparticles with a radius of 2.5, 9, or 15 nm can be usedfor this purpose.

In addition to the above lectures and communica-tions, lectures on the scientific activity of the SosnyBelarussian Research Center (

S. Chigrinov

, Belarus),on radiation chemistry in Poland (

J. Kroh

, Poland), andon the application of pulse radiolysis and computersimulation to studies of the mechanism of radiationpurification of polluted water (

A.K. Pikaev

, Russia).

The following problems were considered in postercommunications: a study of primary radiation-chemi-cal processes in liquids (using hexafluorobenzene and1,2-diphenylindole solutions as an example) by themethod of microwave-induced quantum beats(

S.V. Anishchik et al.

, Russia); the measurement of themobility of geminate radical ions in alkane solutionswith the use of the dependence of delayed lumines-cence on electric field (

S.V. Anishchik et al.

, Russia); acompact unit for picosecond pulse radiolysis with aradiofrequency photocathode (

Y. Aoki et al.

, Japan);electron attachment in gas mixtures containing haloet-hanes (

M. Forys

and coworkers, Poland); the geometry,energy distribution, and lifetime of potential traps forexcess electrons in liquid water (

W. Bartczak

and

K. Pernal

, Poland); a comparison of ionization and ionyield in the ionization column of a high-energy particlewith the Jaffe theory using computer simulation(

M. Bartczak

and

P. Mateja

, Poland); transformationsof phospholipid membranes under the action of thiylradicals in the

cis–trans

isomerization of fatty acid res-idues (

O. Brede

and coworkers, Germany); the fate of apositive charge depending on the lifetime of the anionand the kinetics of geminate recombination with chlo-

rine-containing hydrocarbons in methylcyclohexane(

R. Büler et al.

, Switzerland, Japan); conduction EPRspectroscopy of metal particles in mesoporous materi-als (

M. Danilczuk et al.

, Poland, USA); the peroxidaseactivity of cytochrome C in micellar systems(L. Gebicka, Poland); the protective effect of invertedmicelles in the oxidation of hydrocarbons by peroxidecompounds (J. Gebicki and L. Gebicka, Poland); thestructure–activity relationships for nitroxides and theirprecursors as acceptors in oxidative damages (J. Gleb-ska et al., Poland); a computer simulation of the antiox-idant properties of nitroxides (J. Glebska and M. Zapal-owski, Poland); the behavior of 50-Ω coaxial cables inpulsed bremsstrahlung fields (K. Hodyr, Poland);ultrafast electron transfer in the charge-transfer com-plexes of methylviologen with iodide in water(W. Jarzeba et al., Poland, France); the radiation chem-istry of copper(II) tetrasulfophthalocyanine in thewater–methanol system (J. Kalecinski and coworkers,Poland); the efficiency of electron photoannealing infrozen magnesium chloride–ethylene glycol–metal sul-fophthalocyanine matrices (J. Kalecinski et al.,Poland); the flash photolysis of 4,4'-diphenoxydiphe-nylsulfone (S. Wysotcki and J. Kopania, Poland); aspectroscopic, kinetic, and theoretical study of the rad-ical cations of thioanisole and its carboxyl derivatives(K. Bobrowski and coworkers, Poland); the kinetics ofradical reactions in freon–argon–water and freon–SF6–oxygen gas mixtures (A. Jowko and coworkers,Poland); the drying of silica gel as studied by fluores-cence measurement techniques (E. Miller et al.,Poland); the reactivity of solvated electrons towardmagnesium(II) in water and organic solvents (M. Mos-tafavi and F. Renou, France); a theoretical study of theelectron-beam decomposition of C2H2Cl2 and C2HCl3in dry and wet air (G. Nichipor et al., Belarus, Poland);the reaction of new anthracene derivatives with DNA(R. Ostaszewski et al., Poland); cationic silver clustersin sodalites (J. Perlinska et al., Poland, Japan); thegeometry and energy changes in halomethanes afterelectron capture (B. Pezler, Poland); the photoreduc-tion of ferritin in a mineral core (S. Wysocki andJ. Pietrzak, Poland); electron and positron energylosses in polymers (S. Pimblott et al., USA, the Nether-lands); the reorientation dynamics of azacyclohexadie-nyl radicals in pyridinium tetrafluoroborate (E. Rodu-ner et al., Germany, Poland); the localization of pri-mary electrons in polar liquids depending on the natureof a matrix and on temperature (M. Steblecka andM. Hilczer, Poland); EPR spectroscopy of γ-irradiatedpolycrystalline asparagine and asparagine-containingpeptides (G. Strzelczak et al., Poland, France); a studyof ion recombination in pyrene-doped poly(methylmethacrylate) with the use of wavelength-selectiveradiothermoluminescence (M. Szadkovska-Nice andJ. Mayer, Poland); pulse radiolysis of perfluorinatedsurface compounds and ionomers in aqueous solutions(E. Szajdzinska-Pietek and J. Gebicki, Poland); pulseradiolysis of polypropylene films doped with the anti-

HIGH ENERGY CHEMISTRY Vol. 35 No. 2 2001

PULSE’2000 SIXTH INTERNATIONAL CONFERENCE ON PULSE STUDIES 137

oxidant Irganox (J. Mayer and T. Szreder, Poland);radiation modification of cotton cellulose (E. Takacset al., Hungary); capabilities and applications of theBrookhaven laser accelerator facility (J. Wishart et al.,USA); the preparation of aromatic thioether radical cat-ions containing phenyl, vinyl, allyl, or methyl groups inorganic solvents (P. Wisniowski et al., Poland, Ger-many); a study of the oxidation of α-methylalanine byOH radicals using fast-response EPR spectroscopy andthe spin-trapping technique (G. Hug and P. Wisniowski,Poland); the reactions of CF3CFH , CF2ClCH2 ,and CHF2CH2 radicals with nitrogen oxides (A. Jowkoand coworkers, Poland); the pulse radiolysis of oxygenand the ozone dosimetry of an electron beam in a Sinus-5accelerator (K. Wojciechowski and K. Wnorowski,Poland); a pulse radiolysis study of the protonation ofelectron adducts in the radiation polymerization ofacrylate in an aqueous solution (L. Wojnarovits andcoworkers, Hungary); electron transfer in polyelectro-lyte solutions (M. Wolszak and D. Kowalczyk, Poland);the density functional theory applied to describe excesselectron delocalization in concentrated NaCl andMgCl2 solutions (M. Zapalowski and W. Bartczak,Poland); the methyl group in tetraazamacrocyclic com-plexes as a model of active sites in nickel enzymes(I. Silbermann et al., Israel); and in situ monitoring ofthe radiation polymerization of methyl methacrylate by

measuring the fluorescence from admixed N-(1-pyrene)maleimide (M. Frahn et al., the Netherlands).

The following general conclusions can be drawnfrom the materials of the conference:

(1) Studies of radiation-chemical, photochemical,and radiobiological processes with the use of pulsetechniques remain to be of considerable interest.

(2) State-of-the-art radiation chemistry is character-ized by the development of pulse radiolysis facilitieswith improved time resolution (as short as tenths ofpicoseconds), picosecond electron pulses combinedwith femtosecond laser pulses etc., and by the use ofnew fast-response techniques.

(3) The number of studies on the mechanisms ofradiolytic reactions in practically important systems(supercritical water, systems of biological significance,polluted water, etc.) with the use of pulse techniques isincreasing.

(4) The development of theoretical models for theradiolysis of water and other systems continues.

(5) Pulse techniques (primarily, picosecond andsubpicosecond pulse radiolysis and femtosecond laserphotolysis) find more extensive applications to studiesof the formation dynamics of primary species and therelaxation of ultrafast processes.

O2.

O2.

O2

.