First-principles modeling of x-ray Raman scattering spectra

Abstract

An efficient technique for calculating x-ray Raman scattering spectra at the K edge in the framework of a single-particle theory is presented. It is based on a recursive method to compute the dynamic structure factor as a continued fraction without requiring the explicit calculation of high-lying unoccupied electronic states. Multipole transitions are calculated to provide a full account of the q-dependence of K edges recorded in a series of lithium-bearing reference compounds, namely LiBO 2 , Li 2 CO 3 , Li 2 O, and LiF. The good agreement obtained between experimental and theoretical spectra validates our approach and provides a solid foundation for analyzing K edges beyond the dipole approximation.

Revealing solid electrolyte interphase formation through interface-sensitive Operando X-ray absorption spectroscopy

“…This suggests that peak I no longer corresponds to the EC/DMC electrolyte, but rather decomposition products with a similar XAS feature at the peak I position such as lithium alkyl carbonates (RO(C=O)OLi) e.g. LEC, LMC, LEMC, LEDC 98 , and Li 2 CO 3 100 , 101 . At 0.4 V, peak I* grows at the expense of peak I but both are still discernible.…”

Tandem CO2 Valorization and Ethane Dehydrogenation: Elucidating the Nature of Highly Selective Iron Oxide Active Sites

“…To further investigate the potential structural modifications occurring upon reaction and involving geometry/coordinational changes, Quantum Espresso (QE) DFT code and its Xspectra module, along with FDMNES, , were used for sake of consistency. The theoretical relaxed structure of ideal geometries combining octahedral and tetrahedral structural arrangements were used to calculate O K-edge spectra. , The parameters applied for the self-consistent field (SCF) calculations are summarized in Table S.2 in the Supporting Information. A constant rigid energy shift of 535 eV was applied to all the calculated spectra in order to match the energy range of the experimental data.…”

Revealing Solid Electrolyte Interphase Formation Through Interface-Sensitive Operando X-ray Absorption Spectroscopy

“…LEC, LMC, LEMC, LEDC, [78], and Li 2 CO 3 . [77,113] At 0.4 V, peak I* grows at the expense of peak I but both are still discernible. On further cycling to 0.2 V and below the spectra closely resemble those seen at the same potentials with LP30 in Figure 3.…”