Photon-in/Photon-out Soft-X-Ray SpectroscopySoft-X-Ray Absorption (XAS); Soft-X-Ray Emission (XES)

Resonant Inelastic Soft-X-Ray Scattering (RIXS)

Jinghua Guo (ALS)(a) (b)

XAS,XES: I(w) µ w3SNG(En)|nG,l±1|r|cl>|2

XAS and XES features:

Elemental selectivity Chemical sensitivity Bulk sensitivity

Primary excitation: < 10-15 sDe-excitation: 10-15 s

Resonant Inelastic Soft-X-Ray Scattering

RIXS features: Site selectivity Energy conservation Symmetry selection

(parity conservation) Dynamics Chemical bond probing

RIXS: Resonant Inelastic X-ray Scattering

Kramers-Heisenberg formula:

Appl. to d and f systems, see e.g.: S. Butorin, et al., Phys. Rev. Lett., 77, 574 (1996)

hw´= hw - DEdd

p-core level

EFd,f

hw

Photon in Photon out

Two-photon, core-edge resonanceenhanced valence band excitation

F(w,w´) = S S d(Eg+ w - Ef -w´)f m

<f D m><m D g>Eg + w - Em - iGm

2

Low Energy High Resolution RIXS at Cu M-Edge

Kuiper et al., PRL 80, 5204 (1998)

Sr2CuO2Cl2

Core-hole lifetime does not limit the resolution of RIXS dd-excitations resolved Magnon-excitation (spin flip) resolved

dd

Indirect probing of magnon (spin-flip) excitation

DE = 200 meV at 30 mm slit)

Spin-flip Chiuzbåian et al., PRL 95, 197402 (2005)SLS experiment

NiO

Mueller et al., PRB 46, 11069 (1992).

Science 2000

High-Temperature Superconductivity (HTS) andColossal Magnetoresistance (CMR) Orbital degree of freedom correlation and order-disorder transition strong coupling with charge, spin, and lattice dynamics

RIXS can be used to determine the energy levels

High Resolution Measurements for MnOGhiringhelli et al. (2005)

Resolution: 0.3 eV (FWHM)

Resolution: ~ 0.1 eV

e

Ghiringhelli et al. (2009)

Resolution: 1.6 eV (FWHM)Butorin et al. (1996)

exptatomic calculation

Dispersion (q-dependence) in RIXS of SrCuO2

spinon pair and holon/antiholon excitationL. Duda (Uppsala Univ.) @SLS

spinon pair

holon/antiholon

calculation courtesy of K.Okada

Okayama University

0

5

10

15

20

25

-100 0 100 200 300

Magnetic field dependence of Kondo excitation

(YbInCu4)10T25T27.5T30T32.5T35T40T50T

Energy transfer (meV)

0

1

2

3

-50 0 50 100 150

RIXS Spectra of YbInCu4 at Zero or Strong Magnetic Field

40meV~

0

0.5

1

1.5

-100 0 100 200 300

Kondo resonance for YbInCu4

20meV resolution45meV60meV100meV

Energy transfer (meV)

kBTKSinglet bound state

Magnetic excited states

4f14 +4f13Ck

Akio Kotani (3d-edge, 1500 eV)

O. Fuchs et al., Phys. Rev. Lett. 100 (2008) 027801.T. Tokushima et al., Chem. Phys. Lett. 460 (2008) 387J. Forsberg et al., Phys. Rev. B 79 (2009) 132203

XAFS13 (Stanford), July 2006 By courtesy of S. Shin

Femtosecond dynamics by detuned RIXS

P. Glans et al., Phys. Rev. Lett. 76, 2448 (1996)P. Glans et al., J. Elcetr. Spectr. Rel. Phenom. 82, 3 (1996)

*

Ground state Core state

The resonant excitation O 1s – pu is followed by the ”forbidden” pu – O 1s XES due to dynamical symmetry breaking.Detuning the excitation energy from resonance reduces intensity of ”forbidden” line, indicating restoration of symmetry.

P. Skytt, et al., Phys. Rev. Lett., 77, 5035 (1996)A. Cesar, et al, J. Chem. Phys. 107, 2699 (1997)

Nordgren et al., JCP 76, 3928 (1982)

fsres

1)(

122≤

G+−=

wwτ

fast

slow

O 1s core hole lifetime: < 5 fs (0.15 eV)

w

g

u

g

u

1su1sg

In-situ Electronic Study in Renewable Energy Scientific Challenges

Lithium batteries: higher energy capacity, longer cycle life

SOFC: Enrico Traversa (NIMS, Japan)

Photocatalytic reaction: Artur Braun (EMPA - Swiss Federal Lab's f. Mater. Testing & Research)Electrochemical reaction: Miquel Salmeron (MSD, MF)

Yi Cui, Nature Nanotechnology 3, 31 (2008), Stanford Univ.

Probing Charge Transfer (CT) in Photocatalytic Nanomaterials

H. Frei (PBD) and J.-H. Guo (ALS)Si

Co3O4

Co Co

Co3O4 nanoparticles in nanoporous Silica for Water

Oxidation

O2 yield is 1600 times higher for SBA-15/Co3O4 (35 nm) compared that of bare Co3O4 micron sized particles per weight

F. Jiao and H. Frei, Angew. Chem. 121, 1873 (2009)

Development of in-situ Cells

Co to Ligand transition

Co

e-

Co

Liu et al., Nano Lett. (2007)

Static Liquid Cell

Guo et al., PRL (2002) Guo et al., PRL (2003)

Catalytic Reaction Cell Herranz et al., J. Phys. Chem. B. (2009)

Oxidized Co foil being reduced under 20 torr H2 at ~250 °C.

Si3N4 (100nm)

Cu film (180nm) (WE)Cr (3nm)

Pt wire (CE)

Ag wire (RE)

2 mM NaHCO3

Pote

ntios

tat

X-rays in

1

Fluorescence out Electrochemical Cell

Cyclic Voltammetric (CV) curve