Biomolecular imaging and electronic damage using X-ray free-electron lasers

TL;DR

This paper demonstrates that biomolecular imaging with femtosecond X-ray free-electron lasers is more feasible than previously thought, due to a more accurate imaging model that tolerates electronic damage better.

Contribution

It introduces a detailed imaging model based on optical coherence theory and quantum electrodynamics, challenging prior restrictive estimates for XFEL-based biomolecular imaging.

Findings

More tolerant electronic damage thresholds identified

Nuclear density used as primary structural descriptor

Potential for characterizing electrodynamical processes

Abstract

Proposals to determine biomolecular structures from diffraction experiments using femtosecond X-ray free-electron laser (XFEL) pulses involve a conflict between the incident brightness required to achieve diffraction-limited atomic resolution and the electronic and structural damage induced by the illumination. Here we show that previous estimates of the conditions under which biomolecular structures may be obtained in this manner are unduly restrictive, because they are based on a coherent diffraction model that is not appropriate to the proposed interaction conditions. A more detailed imaging model derived from optical coherence theory and quantum electrodynamics is shown to be far more tolerant of electronic damage. The nuclear density is employed as the principal descriptor of molecular structure. The foundations of the approach may also be used to characterize electrodynamical processes by performing scattering experiments on complex molecules of known structure.