Finite lifetime broadening of calculated x-ray absorption spectra: possible artefacts close to the edge

Abstract

X-ray absorption spectra calculated within an effective one-electron approach have to be broadened to account for the finite lifetime of the core hole. For Green's function based methods this can be achieved either by adding a small imaginary part to the energy or by convoluting the spectra on the real axis with a Lorentzian. We demonstrate on the case of Fe K and L2,3 spectra that these procedures lead to identical results only for energies higher than few core level widths above the absorption edge. For energies close to the edge, spurious spectral features may appear if too much weight is put on broadening via the imaginary energy component. Special care should be taken for dichroic spectra at edges which comprise several exchange-split core levels, such as the L3 edge of 3d transition metals.

arXiv comment6 pages, 4 figures, 2 tables

References in corpus (6)

• Theoretical X-Ray Absorption Debye-Waller Factors
• Multiple-Scattering Theory of X-Ray Magnetic Circular Dichroism: Implementation and Results for Iron K-edge
• Ab initio calculations of mean free paths and stopping powers
• Many-body effects in x-ray absorption and magnetic circular dichroism spectra within the LSDA+DMFT framework
• Effects of electronic correlation on X-Ray absorption and dichroic spectra at L${}_{2,3}$ edge
• Including atomic vibrations in XANES calculations: polarization-dependent damping of the fine structure at the Cu K edge of (creat)${}_2$CuCl${}_4$

Cited by in corpus (1)

• Spin-spiral state of a Mn monolayer on W(110) studied by soft x-ray absorption spectroscopy at variable temperatures