| 1. |
- Olovsson, Weine, 1975-, et al.
(författare)
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Vibrational Effects in X-ray Absorption Spectra of Two-Dimensional Layered Materials
- 2019
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Ingår i: The Journal of Physical Chemistry C. - : ACS Publications. - 1932-7447 .- 1932-7455. ; 123:15, s. 9688-9692
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Tidskriftsartikel (refereegranskat)abstract
- With the examples of the C K-edge in graphite and the B K-edge in hexagonal boron nitride, we demonstrate the impact of vibrational coupling and lattice distortions on the X-ray absorption near-edge structure (XANES) in two-dimensional layered materials. Theoretical XANES spectra are obtained by solving the Bethe–Salpeter equation of many-body perturbation theory, including excitonic effects through the correlated motion of the core hole and excited electron. We show that accounting for zero-point motion is important for the interpretation and understanding of the measured X-ray absorption fine structure in both materials, in particular for describing the σ*-peak structure.
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| 2. |
- Tomita, Kota, et al.
(författare)
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Core-Exciton Interaction in Sodium L-2,L-3 edge Structure Investigated Using the Bethe-Salpeter Equation
- 2016
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 120:17, s. 9036-9042
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Tidskriftsartikel (refereegranskat)abstract
- Despite the importance of sodium compounds for their application in sodium-ion rechargeable batteries, core-exciton interactions in sodium L-2,L-3 edge core-electron loss spectra are not well-understood. In this study, Bethe-Salpeter equation calculations of sodium L-2,L-3 edges of sodium compounds were performed to understand the relationships between the core-exciton interactions and the electronic structure of sodium compounds. It was revealed that the core-exciton interaction of sodium compounds is strongly dependent on the compounds. We found that neither band gap nor ionic charge can explain the trend; however, the transition energy shows a clear correlation to the magnitude of the core-exciton interaction. These results indicate that the magnitude of the core-exciton interaction is decided by the excited electronic structure of each compound.
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| 3. |
- Tomita, Kota, et al.
(författare)
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Strong excitonic interactions in the oxygen K-edge of perovskite oxides
- 2017
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Ingår i: Ultramicroscopy. - : ELSEVIER SCIENCE BV. - 0304-3991 .- 1879-2723. ; 178, s. 105-111
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Tidskriftsartikel (refereegranskat)abstract
- Excitonic interactions of the oxygen IC edge electron energy-loss near-edge structure (ELNES) of perovskite oxides, CaTiO3, SrTiO3, and BaTiO3, together with reference oxides, MgO, CaO, SrO, BaO, and TiO2, were investigated using a first -principles Bethe-Salpeter equation calculation. Although the transition energy of oxygen K-edge is high, strong excitonic interactions were present in the oxygen K-edge ELNES of the perovskite oxides, whereas the excitonic interactions were negligible in the oxygen IC edge ELNES of the reference compounds. Detailed investigation of the electronic structure suggests that the strong excitonic interaction in the oxygen K-edge ELNES of the perovskite oxides is caused by the directionally confined, low-dimensional electronic structure at the Ti-O-Ti bonds. (C) 2016 Elsevier B.V. All rights reserved.
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