Figure 1. Schematic of T-jump TRX experiment.

Lysozyme crystals were delivered to the pump-probe interaction region via a microfluidic jet. Light and dark images were collected in an interleaved manner, with light images defined as those where the crystal was pumped with an IR laser at a defined time-delay ($\mathrm{\Delta }\mathrm{t}$) prior to being probed by the XFEL. Dark images were collected with the IR pump shutter closed and an XFEL probe. These images were combined in post-processing to create a set of structure factors for each time delay (${\mathrm{F}}_{\mathrm{t}}$) and as well as two corresponding sets of dark structure factors (${\mathrm{F}}_{\mathrm{d}\mathrm{a}\mathrm{r}\mathrm{k}1}$ and ${\mathrm{F}}_{\mathrm{d}\mathrm{a}\mathrm{r}\mathrm{k}2}$). Experiments and matching controls as defined above and in the text were analyzed to identify time-dependent structural changes.