Radiation damage in room-temperature data acquisition with the PILATUS 6M pixel detector

Observations of the dose-rate effect in continuous X-ray diffraction data acquisition at room temperature are presented.

was measured with a thermocouple which was kept within ~3 mm distance from the sample.
The state of the insulin crystals before and after data collection at the different temperatures as observed with the sample alignment microscope is shown in figure S1. Each data set corresponds to 45° (90 images of 0.5° oscillation angle), with 0.64 s / frame exposure time at a flux of ~2.5 to 2.9 × 10 10 ph / sec. The beam size was 100 µm by 80 µm. These parameters correspond to a dose of ~8.9 × 10 4 Gy per data set      Plot of the change in R meas of successive datasets for insulin crystals I_12, I_6, I_3 and I_1. The resolution range used for the calculation is between 4.8 -1.6 Å.

Figure S3
Plot of the change in R meas of successive datasets for thaumatin crystals T_12, T_6, T_3 and T_1. The resolution range used for the calculation is between 4.8-1.6 Å Figure S4 Plot of the change in I/σI of successive datasets for insulin crystals I_12, I_6, I_3 and I_1. The resolution range used for the calculation is between 4.8 -1.6 Å.

Figure S5
Plot of the change in I/σI of successive datasets for thaumatin crystals T_12, T_6, T_3 and T_1. The resolution range used for the calculation is between 4.8-1.6 Å.

Figure S6
Plot of the change in mosaicity of successive datasets for insulin crystals I_12, I_6, I_3 and I_1. The resolution range used for the calculation is between 4.8 -1.6 Å.

Figure S7
Plot of the change in mosaicity of successive datasets for thaumatin crystals T_12, T_6, T_3 and T_1. The resolution range used for the calculation is between 4.8-1.6 Å Supplementary material -3

UV-Vis absorption spectroscopy experiments
The change in optical density (OD) in the visible range of an insulin crystal irradiated by ten X-ray beam pulses (where each is of 1 s length and separated by 4 s without irradiation) was measured by means of the co-axial microspectrophotometer installed at SLS beamline X10SA (Owen et al., 2009). The X-ray beam size was ~110 µm by 90 μm, while the spot size of the microspectrophotometer illumination was 50 µm by 50 µm. Absorption data were recorded using an ANDOR Shamrock Czerny-Turner spectrograph, using entrance slit sizes of 10 µm and an optical grating with 150 lines/mm, blazed at 300 nm. Kinetic spectra were acquired with an acquisition time of 3.42 ms and cycle frequency of 48.92 Hz (20.44 ms). The dose per second of the X-ray beam irradiation was calculated using RADDOSE (Murray et al., 2004) to be 9 × 10 3 Gy. The temporal evolution of the signal at 400 nm and 600 nm was measured at 100 K ( Figure S8a) and at 298 K ( Figure S8c). The absorbance at 400 nm and 600 nm corresponds to disulfide radical anions and trapped electrons respectively (McGeehan et al., 2009). At 100 K we could not observe any signature of trapped electrons.
No indication of either of the radiolytic products could be detected at RT ( Figure S8c).

Figure S8
The optical density of an insulin crystal irradiated for 10 beam pulses of 1s each, separated by 4 s without X-ray irradiation, followed at 400 nm and from 520-620 nm in 20 nm steps at 100 K ( Figure S8