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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´= h w - DEdd
p-core level
EF
d,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-flipChiuzbåian 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 MnO
Ghiringhelli 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)
kBTK
Singlet 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≤
Γ+−=
ωωτ
fast
slow
O 1s core hole lifetime: < 5 fs (0.15 eV)
w
g
u
g
u
1su
1sg
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 outElectrochemical Cell
Cyclic Voltammetric (CV) curve