Imaging interatomic electron current in crystals with ultrafast resonant x-ray scattering

TL;DR

This paper demonstrates how ultrafast resonant x-ray scattering can image electronic wave packet dynamics in crystals by capturing interatomic electron currents from single scattering patterns, even with inelastic scattering effects.

Contribution

It introduces a method to extract interatomic electron currents from scattering patterns in crystals, accounting for inelastic scattering effects, and provides practical examples with specific crystal clusters.

Findings

Scattering patterns encode instantaneous electron currents.

Interatomic electron current can be extracted from a single pattern.

Method works with broad-band probe pulses in crystals.

Abstract

We demonstrate how the technique of ultrafast resonant x-ray scattering can be applied to imaging dynamics of electronic wave packets in crystals. We study scattering patterns from crystals with electron dynamics in valence bands taking into account that inelastic and elastic scattering events induced by a broad-band probe pulse cannot be separated through the spectroscopy of the scattered photon. As a result, scattering patterns are not determined by the structure factor at the time of measurement, but can encode the instantaneous electron current between scattering atoms. We provide examples of how the interatomic electron current in a periodic structure can be extracted from a single scattering pattern by considering valence electron hole motion in (KBr)$_{108}$ and Ge$_{83}$ clusters.