Topics Interaction of X-rays with matter Overview of core level - PowerPoint PPT Presentation

Charge Transfer Effects 2  +U 15 3U-2  Energy (eV) 10 5  U-  0 6 7 8 9 10 3d count

Charge Transfer Effects in XAS 15 Energy (eV)  +U-Q 10 5  0 6 7 8 9 10 3d count

Charge Transfer Effects MnO: Ground state: 3d 5 + 3d 6 L Energy of 3d 6 L: Charge transfer energy  3d 6 L 2p 5 3d 7 L   +U-Q   2p 5 3d 6 3d 5

Charge Transfer Effects in XPS 15 Energy (eV) 10  -Q  5 0 6 7 8 9 10 3d count

Charge transfer effects in XAS and XPS • Transition metal oxide: Ground state: 3d 5 + 3d 6 L • Energy of 3d 6 L: Charge transfer energy  3d 6 L XPS XAS  2p 5 3d 5 3d 5 2p 5 3d 7 L  -Q Ground State  +U-Q   2p 5 3d 6 L 2p 5 3d 6

X-ray Absorption Spectroscopy Spectral shape: (1) Multiplet effects (2) Charge Transfer J. Elec. Spec. 67, 529 (1994)

Charge Transfer effects 3d 8 + 3d 9 L  =10 30% 3d 8 1 A 1  =5 NiO  =0 30% 3d 8 La 2 Li ½ Cu ½ O 4  =-5 3 A 2  =-10 Chem. Phys. Lett. 297, 321 (1998)

LMCT and MLCT:  - bonding Fe III : Ground state: 3d 5 + 3d 6 L N N N N C C C C M M M M C C C C N N N N M M M M filled  - filled  - filled  - filled  - empty d or p empty d or p empty d or p empty d or p empty filled filled filled filled filled empty empty empty empty      3d 6 L 2p 5 3d 7 L     +U-Q   2p 5 3d 6 3d 5 with Ed Solomon (Stanford) JACS 125, 12894 (2003), JACS 128, 10442 (2006), JACS 129, 113 (2007)

LMCT and MLCT:  - bonding Fe III : Ground state: 3d 5 + 3d 6 L + 3d 4 L 2p 5 3d 5 L 3d 4 L   -U+Q    + 2   3d 6 L 2p 5 3d 7 L   +U-Q   - 2 2p 5 3d 6 3d 5 with Ed Solomon (Stanford) JACS 125, 12894 (2003), JACS 128, 10442 (2006), JACS 129, 113 (2007)

LMCT and MLCT:  - bonding Fe III (tacn) 2 10 Fit X Normalized Absorption Series2 8 Fe III (CN) 6 6 4 2 0 700 705 710 715 720 725 730 -2 with Ed Solomon (Stanford) JACS 125, 12894 (2003), Energy (eV) JACS 128, 10442 (2006), JACS 129, 113 (2007)

resonant inelastic x-ray scattering

resonant inelastic x-ray scattering a.k.a. resonant x-ray Raman Ψ 0 3 2 1 0

resonant inelastic x-ray scattering

Why RIXS? • Measure optical spectra with x-rays >> in-situ, element/valence specific • dd-transitions > electronic structure • Magnetic excitations • Select specific states (active sites) (only soft x-ray RIXS)

2p3d RIXS and magnetic excitations (NiO)  S  M S dd ‘spin - flip’ spin-flip [Phys. Rev. B. 57, 14584 (1998)]

2p3d RIXS of CoO MCD, spin, angles polarization, angular-dependence (in, sample, out) eV meV 2-electron integrals spin-orbit, magnetic crystal field distortions charge transfer vibrations

2p3d resonant XES of Co-carboxylates (1) (2) (3) (4) van Schooneveld et al., Angew. Chem. 52, 1170 (2012)

2p3d RIXS of CoO 4.2 nm [van Schooneveld, J. Phys. Chem. C. 116, 15218 (2012)]

2p3d RIXS of CoO

Select specific states in 2p3d RIXS (Fe 3 O 4 ) exchange 707.2 706.7 Incident photon energy (eV) 706.3 706.3 705.9 705.5 705.9 Intensity (arb. units) 50 705 705.5 40 704.5 30 704 705 20 704.5 703.5 10 0 704 703 703.5 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 703 Energy loss (eV) -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 Energy loss (eV) spin-orbit + exchange [Huang et al. arXiv:1512.07957 ]

Select specific states in 2p3d RIXS (Fe 3 O 4 ) exchange 707.2 706.7 Incident photon energy (eV) 706.3 706.3 705.9 Interference shows that lifetime broadening 705.5 705.9 Intensity (arb. units) (fwhm) is only 100 meV, not 200 meV 50 705 705.5 40 704.5 30 704 705 20 20 fs >>> 40 fs 704.5 703.5 10 0 704 703 703.5 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 703 Energy loss (eV) -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 Energy loss (eV) spin-orbit + exchange [Huang et al. arXiv:1512.07957 ]

2p3d resonant XES of metal Co nanoparticles [van Schooneveld, J. Phys. Chem. Lett 4, 1161 (2013)]