Removal of core hole distortion from ionization edges in electron energy loss spectroscopy

Abstract

The near-edge fine structure in electron energy loss spectra is used to probe the electronic bonding environment of materials at high spatial resolution. Often, however, deviations from the ground state electronic properties are observed, due to the core hole created within the ionized atom. A method is proposed to remove core hole distortion from experimental electron energy loss spectra by calculating the electrodynamic work done in separating the moving, incident electron from the oppositely charged core hole. Dynamic screening of the core hole is modeled using the material dielectric properties. The resulting energy gain spectrum is deconvolved from the experimental measurement to give a ``fully screened'' spectrum that is free of core hole distortion. The method is tested on core loss edges in elemental Si, SiC, and ${\mathrm{SiO}}_{x}$. Despite assuming classical electrodynamics, the fundamental principle of an energy gain correction can be shown to be consistent with quantum mechanics, although shortcomings in some of the assumptions made on the nature of the core hole are also identified.