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Figure 11
Micrograph of an SOS chip loaded with DtpAa microcrystals taken shortly after data collection at Cristallina-MX. The X-ray rastering step sizes were 10 × 10 µm within and between line scans, respectively. The regular array of small comma-shaped features (pointed out by red arrows) visible over the entire micrograph was created by the individual XFEL shots. Due to imperfect registry during the commissioning experiment of the scan translation stages (which in fact was identified in this way), these craters do not form a regular Cartesian array. This is of no major concern for SOS measurements (for a structured solid chip it would be dreadful). In addition to the regular array of craters there are some much larger circular features of varying sizes, possibly created by desiccation around certain anomalous holes punched by the XFEL beam or by the nucleation and growth of bubbles of gases generated by XFEL exposure. Moreover, several DtpAa crystals show a bulging torus (marked by red circles). We have often seen what appear to be `ejecta blankets' where the XFEL beam has hit a crystal as opposed to liquid, and have associated this with a more violent interaction of the X-ray beam with the crystal matter than with the buffer liquid. The torus is next to but not around a neighboring small crater, possibly due to crystal or foil movement after X-ray data collection. The camera was focused on the upper SOS foil.

IUCrJ
Volume 12| Part 6| November 2025| Pages 692-709
ISSN: 2052-2525
https://doi.org/10.1107/S2052252525008371