Theory of X-ray absorption spectroscopy: a microscopic Bloch equation approach for two-dimensional solid states

TL;DR

This paper introduces a microscopic Bloch equation approach to X-ray absorption spectroscopy in two-dimensional materials, enabling detailed analysis of spectral features and many-body interactions.

Contribution

It develops a self-consistent Maxwell-Bloch formalism incorporating Bloch theorem and Coulomb interactions for 2D crystalline materials, applied to graphene.

Findings

Accurate modeling of spectral oscillations in EXAFS.

Assignment of previously uninterpreted spectral features.

Insights into many-body effects in X-ray absorption.

Abstract

We develop a self-consistent Maxwell-Bloch formalism for the interaction of X-rays with two-dimensional crystalline materials by incorporating the Bloch theorem and Coulomb many-body interaction. This formalism is illustrated for graphene, by calculating the polarization-dependent XANES, formulating expressions for the radiative and Meinter-Auger recombination of core-holes, and the discussion of microscopic insights into the spectral oscillations of EXAFS beyond point scattering theory. In particular, the correct inclusion of lattice periodicity in our evaluation allows us to assign so far uninterpreted spectral features in the Fourier transformed EXAFS spectrum.