Auger Electron Cascades in Water and Ice

TL;DR

This paper investigates Auger electron cascades in water and ice, revealing how secondary electron generation affects radiation damage in X-ray imaging of biomolecular samples.

Contribution

It provides new simulation results on electron-induced damage in water and ice, comparing theoretical estimations with experimental data and analyzing damage differences.

Findings

Average secondary electrons in ice: ~25 after 100 fs

Average secondary electrons in water: ~20 after 100 fs

Good agreement between theory and experiment for elastic cross sections

Abstract

Secondary electron cascades can induce significant ionisation in condensed matter due to electron-atom collisions. This is of interest in the context of diffraction and imaging using X-rays, where radiation damage is the main limiting factor for achieving high resolution data. Here we present new results on electron-induced damage on liquid water and ice, from the simulation of Auger electron cascades. We have compared our theoretical estimations to the available experimental data on elastic and inelastic electron-molecule interactions for water and found the theoretical results for elastic cross sections to be in very good agreement with experiment. As a result of the cascade we find that the average number of secondary electrons after 100 fs in ice is about 25, slightly higher than in water, where it is about 20. The difference in damage between ice and water is discussed in the context of sample handling for biomolecular systems.