Impact of ultrafast electronic damage in single particle x-ray imaging experiments

TL;DR

This paper investigates how ultrafast electronic damage affects single particle x-ray imaging at XFELs, showing that significant contrast loss occurs only at extremely high fluences beyond current capabilities.

Contribution

It quantifies the impact of electronic damage on diffraction pattern quality and identifies the fluence thresholds where damage becomes significant.

Findings

Contrast reduction occurs only at very high fluences

Electronic damage introduces a strong isotropic background

Current XFEL sources are below damage-inducing fluence levels

Abstract

In single particle coherent x-ray diffraction imaging experiments, performed at x-ray free-electron lasers (XFELs), samples are exposed to intense x-ray pulses to obtain single-shot diffraction patterns. The high intensity induces electronic dynamics on the femtosecond time scale in the system, which can reduce the contrast of the obtained diffraction patterns and adds an isotropic background. We quantify the degradation of the diffraction pattern from ultrafast electronic damage by performing simulations on a biological sample exposed to x-ray pulses with different parameters. We find that the contrast is substantially reduced and the background is considerably strong only if almost all electrons are removed from their parent atoms. This happens at fluences of at least one order of magnitude larger than provided at currently available XFEL sources.