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| 3. |
- Butorin, Sergei, et al.
(författare)
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Electronic structure of americium sesquioxide probed by resonant inelastic x-ray scattering
- 2023
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 108:19
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Tidskriftsartikel (refereegranskat)abstract
- The Am 5d-5f resonant inelastic x-ray scattering (RIXS) data of americium sesquioxide were measured at incident photon energies throughout the Am O4,5 edges. The experiment was supported by calculations using several model approaches. While the experimental Am O4,5 x-ray absorption spectrum of Am2O3 is compared with the spectra calculated in the framework of atomic multiplet and crystal-field multiplet theories and Anderson impurity model (AIM) for the Am(III) system, the recorded Am 5d-5 f RIXS data are essentially reproduced by the crystal-field multiplet calculations. A combination of the experimental scattering geometry and theoretical analysis of the character of the electronic states probed during the RIXS process confirms that the ground state of Am2O3 is singlet P1. An appearance of the low-intense charge-transfer satellite in the Am 5d-5 f RIXS spectra at an energy loss of similar to 5.5 eV suggests weak Am 5 f-O 2p hybridization which is in agreement with AIM estimations of the 5 f occupancy from spectroscopic data in Am2O3 as being 6.05 electrons.
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| 4. |
- Butorin, S. M., et al.
(författare)
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Resonant inelastic soft X-ray scattering at the 4d edge of Ce-based heavy fermion materials
- 1999
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 101-103, s. 783-786
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Tidskriftsartikel (refereegranskat)abstract
- Resonant X-ray scattering measurements were performed on CeB6, CeAl, γ-Ce, and α-Ce at various incident-photon energies near the Ce 4d threshold. A pronounced inelastic scattering structure which has 4f character is observed at about 4 eV below the elastic peak. The structure shows a distinct resonant behavior as well as a dependence on the degree of 4f hybridization and can therefore be attributed to charge-transfer excitations to the 4f0 state. The intensity of the elastic peak increases when going from the systems with low Kondo temperature TK to those with high TK which is consistent with a Kondo scale behavior. By analyzing the scattering data, a controversial issue on the validity of a single-impurity Anderson model in heavy-fermion materials is addressed.
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| 5. |
- Butorin, S. M., et al.
(författare)
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Resonant inelastic soft X-ray scattering studies of U(VI) reduction on iron surfaces
- 2004
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Ingår i: Materials Research Society Symposium Proceedings. - 0272-9172 .- 1946-4274. ; 807:Scientific Basis for Nuclear Waste Management XXVII, s. 113-118
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Tidskriftsartikel (refereegranskat)abstract
- The authors report on the spectroscopic anal. of several samples relevant to the processes governing the behavior of oxidized U species in groundwater solns. under anoxic conditions. Both Fe samples with different times of exposure to the U(IV) soln. and Fe metal-soln. interfaces in the liq. cell ex-situ and in-situ, resp. Resonant inelastic soft x-ray scattering is sensitive to the chem. state of U. The measurements were performed at a no. of energies of the primary photon beam across the U 5d absorption edge. The results unambiguously indicate the redn. of U(VI) to U(IV) on the Fe surface. [on SciFinder(R)]
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| 7. |
- Guo, J.-H., et al.
(författare)
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Molecular structure of alcohol-water mixtures
- 2003
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 91:15
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Tidskriftsartikel (refereegranskat)abstract
- We use x-ray emission spectroscopy to elucidate the molecular structure of liquid methanol, water, and methanol-water solutions. We find that molecules in the pure liquid methanol predominantly persist as hydrogen-bonded chains and rings with six and/or eight molecules of equal abundance. For water-methanol solutions we find evidence of incomplete mixing at the microscopic level. Our results provide a new explanation for a smaller entropy increase in the solution due to water molecules bridging methanol chains to form rings.
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| 8. |
- Guo, J. H., et al.
(författare)
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The molecular structure of alcohol-water mixtures determined by soft-X-ray absorption and emission spectroscopy
- 2004
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 137-40:SI, s. 425-428
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Tidskriftsartikel (refereegranskat)abstract
- We have examined the influence of the intermolecular interaction on the local electronic structure by using X-ray absorption and emission spectra of liquid methanol, water, and their mixtures (in molar ratios of 9:1 and 7:3). We find a strong involvement of hydrogen bonding in the mixing of water and methanol molecules. The local electronic structure of water and methanol clusters, where water cluster is bridging within a 6-member open-ring structured methanol cluster, is separately determined. The experimental findings suggest an incomplete mixing of water-alcohol systems and a strong self- association between methanol chain and water cluster through hydrogen bonding. The enhancement of joint water-methanol open-ring structure owes the explanation to the loss of entropy of the aqueous solutions.
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| 9. |
- Modin, Anders, et al.
(författare)
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5 f-Shell correlation effects in dioxides of light actinides studied by O 1s x-ray absorption and emission spectroscopies and first-principles calculations
- 2015
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 27:31
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Tidskriftsartikel (refereegranskat)abstract
- Soft x-ray emission and absorption spectroscopic data are reported for the O 1s region of a single crystal of UO2, a polycrystalline NpO2 sample, and a single crystal of PuO2. The experimental data are interpreted using first-principles correlated-electron calculations within the framework of the density functional theory with added Coulomb U interaction (DFT+U). A detailed analysis regarding the origin of different structures in the x-ray emission and x-ray absorption spectra is given and the effect of varying the intra-atomic Coulomb interaction-U for the 5f electrons is investigated. Our data indicate that O 1s x-ray absorption and emission spectroscopies can, in combination with DFT+U calculations, successfully be used to study 5f-shell Coulomb correlation effects in dioxides of light actinides. The values for the Coulomb U parameter in these dioxides are derived to be in the range of 4-5 eV.
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