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| 3. |
- Agåker, Marcus, et al.
(författare)
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Resonant inelastic soft x-ray scattering at double core excitations in solid LiCl
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 73:24
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Tidskriftsartikel (refereegranskat)abstract
- Inelastic soft x-ray scattering in LiCl, resonantly enhanced at states with two Li 1s vacancies, is investigated. States in which both excited electrons are localized during the double core hole lifetime, in which one of the electrons delocalize, as well as triply excited states in which the double core excitation is accompanied by a valence-to-conduction band excitation, contribute to the scattering. The angular momentum symmetry of the involved states and the vibronic coupling during the scattering process are reflected in the angular anisotropy. The effect on the local electronic structure of multiple core holes is theoretically studied by means of supercell band calculations.
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| 4. |
- Galakhov, V. R., et al.
(författare)
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Electronic structure and x-ray spectra of defective oxides LixCoO2
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:4, s. 045120-
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Tidskriftsartikel (refereegranskat)abstract
- X-ray absorption, resonant x-ray emission, and x-ray photoelectron spectra of the valence band and core levels have been measured for LixCoO2 (0.6 <= x <= 1.0). Resonant O K alpha x-ray emission spectra of LiCoO2 showed localized excitonic states due to a dd transition between unoccupied and occupied Co 3d states. On the basis of measurements of Co 3s x-ray photoelectron and Co 2p and O 1s x-ray absorption spectra it was established that in defective cobaltites the electronic holes are localized mainly in O 2p states. Evidence of phase separation in LixCoO2 has been found.
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| 5. |
- Kikas, A, et al.
(författare)
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Resonant inelastic X-ray scattering at the K edge of oxygen and fluorine in insulators
- 2005
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 144-147, s. 845-848
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Tidskriftsartikel (refereegranskat)abstract
- Here we present the results of a study of the electronic structure using the resonant inelastic scattering process at the F 1s photoabsorption edge in LiF and O 1s edge of MgO crystals. In case of excitations in the sub-threshold region, the Raman-type linear dispersion of X-ray fluorescence peak was observed for the studied compounds. In LiF, the narrowing of the X-ray fluorescence peak is observed at pre-threshold excitation, which can be related to the creation of a core exciton, but no core excitons were identified in MgO.
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| 7. |
- Kjeldgaard, Lisbeth, et al.
(författare)
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Intramolecular vibronic dynamics in molecular solids: C60
- 2005
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 72:20
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Tidskriftsartikel (refereegranskat)abstract
- Vibronic coupling in solid C60 has been investigated with a combination of resonant photoemission spectroscopy (RPES) and resonant inelastic x-ray scattering (RIXS). Excitation as a function of energy within the lowest unoccupied molecular orbital resonance yielded strong oscillations in intensity and dispersion in RPES, and a strong inelastic component in RIXS. Reconciling these two observations establishes that vibronic coupling in this core hole excitation leads to predominantly inelastic scattering and localization of the excited vibrations on the molecule on a femtosecond time scale. The coupling extends throughout the widths of the frontier valence bands.
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| 8. |
- Käämbre, Tanel, et al.
(författare)
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Bulk electronic structure of K3C60 as revealed by soft x-rays
- 2007
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75:19, s. 195432-
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Tidskriftsartikel (refereegranskat)abstract
- We present C 1s x- ray absorption, x- ray emission, and resonant inelastic x- ray scattering (RIXS ) spectra of single- phase crystalline K3C60. The comparison to valence- band photoelectron spectra from the same sample facilitates identification of the contribution from surface and bulk electronic states in the latter. Bulk- sensitive techniques show that the valence bands of K3C60 and pure C-60 are characterized by spectral features of similar width, in agreement with the predictions of band- structure calculations. Symmetry selectivity in the RIXS process allows us to assign peaks in the C 1s absorption spectrum, demonstrating a close correspondence with pure C-60 also in the conduction band. The symmetry selectivity is as pronounced in K3C60 as in pure C-60, indicating that the local C-60 symmetry is not appreciably affected by the K doping, either in the ground state or intermediate state, on the time scale of 6 fs.
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| 9. |
- Modin, A., et al.
(författare)
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Closed source experimental system for soft x-ray spectroscopy of radioactive materials
- 2008
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 79:9, s. 093103-
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Tidskriftsartikel (refereegranskat)abstract
- An instrumental and experimental setup for soft x-ray spectroscopy meeting the requirements of a closed source for radioactivity is described. The system consists of a vacuum sealed cell containing the sample, mounted on a tubing system to ensure compatibility with most standard manipulators. The soft x rays penetrate a thin x-ray window separating the interior of the cell from the vacuum in the experimental chamber. Our first results for single crystal PuO2 confirm the feasibility of experiments using the setup. The results are consistent with results of first principles calculations and previously recorded spectra obtained using a standard open source setup. The results show that the closed source experimental system can be used to collect valuable experimental data from radioactive materials.
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| 10. |
- Preobrajenski, Alexei, et al.
(författare)
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Adsorption-induced gap states of h-BN on metal surfaces
- 2008
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 77:8, s. 085421-
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Tidskriftsartikel (refereegranskat)abstract
- The formation of hexagonal boron nitride (h-BN) monolayers on Ni(111), Rh(111), and Pt(111) has been studied by a combination of x-ray emission, angle-resolved valence band photoemission, and x-ray absorption in search for interface-induced gap states of h-BN. A significant density of both occupied and unoccupied gap states with N 2p and B 2p characters is observed for h-BN/Ni(111), somewhat less for h-BN/Rh(111) and still less for h-BN/Pt(111). X-ray emission shows that the h-BN monolayer is chemisorbed strongly on Ni(111) and very weakly on Pt(111). We associate the gap states of h-BN adsorbed on the transition metal surfaces with the orbital mixing and electron sharing at the interface because their density increases with the growing strength of chemisorption.
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