Abstract
The prospect of single particle imaging with atomic resolution is one of the scientific drivers for the development of X-ray free-electron lasers. The assumption since the beginning has been that damage to the sample caused by intense X-ray pulses is one of the limiting factors for achieving subnanometer X-ray imaging of single particles and that X-ray pulses need to be as short as possible. Based on the molecular dynamics simulations of proteins in X-ray fields of various durations (5 fs, 25 fs, and 50 fs), we show that the noise in the diffracted signal caused by radiation damage is less than what can be expected from other sources, such as sample inhomogeneity and X-ray shot-to-shot variations. These findings show a different aspect of the feasibility of high-resolution single particle imaging using free-electron lasers, where employing X-ray pulses of longer durations could still provide a useful diffraction signal above the noise due to the Coulomb explosion.
Highlights
X-ray crystallography has so far proven to be the most successful technique for determining three-dimensional molecular structures at atomic resolution and has been instrumental in a number of scientific fields
Based on the molecular dynamics simulations of proteins in X-ray fields of various durations (5 fs, 25 fs, and 50 fs), we show that the noise in the diffracted signal caused by radiation damage is less than what can be expected from other sources, such as sample inhomogeneity and X-ray shot-to-shot variations
Building on our recent study of the explosion dynamics of proteins exposed to an X-ray free-electron lasers (XFELs) pulse,[8] we investigated how the Coulomb explosion contributes to the noise in the diffracted signal
Summary
X-ray crystallography has so far proven to be the most successful technique for determining three-dimensional molecular structures at atomic resolution and has been instrumental in a number of scientific fields. Synchrotron-based X-ray crystallography, the periodic structure that makes up the crystal amplifies the diffracted signal and results in an interference pattern with sharp peaks in intensity. These so-called Bragg spots encode for the desired structural information, and their brightness is highly dependent on the size of the crystal. The only usable features for structure determination that remain, often referred to as speckles, arise from interfering waves from different atoms within the same molecule. In this case, a different approach is necessary
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