First Principles Study of Core-hole Effect on Fluorine K-edge X-ray Absorption Spectra of MgF<SUB>2</SUB> and ZnF<SUB>2</SUB>

Abstract

First principles calculations have been carried out to investigate the core-hole effects on the theoretical fine structures of the X-ray absorption spectra of MgF 2 and ZnF 2 at F K-edge. Significant differences are found between the calculated spectral fine structures with and without core-holes. Experimental profiles of the near-edge X-ray absorption fine structures are well reproduced by the theoretical ones when the core-hole effect is introduced. The dependence of supercell size on the theoretical fine structures is also examined.

Excitonic Effects in X-ray Absorption Spectra of Fluoride Salts and Their Surfaces

“…At first glance, it is clear that while spectral line shapes for a given salt agree approximately between different measurements (and with our calculations) their energy alignment can vary significantlyfrom essentially 0 eV for CaF 2 up to ∼1.8 eV for ZnF 2 . This experimental variation is larger than the experimental energy resolution, which ranges up to 0.4 eV. , In the case of LiF, for instance, there seem to be two types of alignments in the literature, with the main edge peak either at ∼ 692.0 , or ∼ 694 eV. , However, the latter data are aligned to a non-resonant inelastic X-ray scattering experiment with an energy resolution of only 1.9 eV, and so, perhaps, we could realign them to the former higher resolution datathe line shapes agree very well.…”

“…Calculated crystal (black) and temperature-averaged (green) spectra of reference solids are shown in the bottom part of each subplot, with their corresponding experimental spectra on the top part: LiF (a), ,, NaF (b), , KF (c), ,, MgF 2 (d), , CaF 2 (e), , and ZnF 2 (f). , Each set of experiments is shown in a different color. Note that the only true bulk absorption measurement is that of Oizumi et al (orange), while all others use some form of surface-sensitive electron yield.…”

Temperature and radiation effects at the fluorine K-edge in LiF

“…The LiF defect structure consisted of a single missing F atom in a 3 × 3 × 3 supercell (215 atoms), and the ionic positions were relaxed. The transition energy was determined based on total energy differences as compared to a known standard MgF 2 using the XCH scheme detailed previously [24]. The crystal coordinates of Li and F in LiF were taken from the literature [25], and used as a starting point for generation of distributions of atomic positions at various temperatures.…”

F-doping of nanostructured ZnO: a way to modify structural, electronic, and surface properties

“…The F K-Edge spectra are given in the ESI † and show the presence of ZnF 2 in the spectrum for ZnO_F10. 46 3.4 Surface acid-base properties of fluorine treated ZnO 3.4.1 IR spectroscopic analysis of the surface acidity probed by NH 3 adsorption. The NEXAFS data indicate an increased ionicity of the system.…”