Data collection: Tips and Tricks
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See also cryo and Crystal growth: Tips and Tricks#Reducing the mosaicity, and Improving crystal quality.
The following tips mostly refer to cryo improvement:
- PEG3350 seems to be little too large for freezing, particularly in presence of high salt concentration. However, PEG2000 is good enough as a cryo protectant.
- Try oils for cryoprotection
- Try stepwise increase from low concentrations of cryoprotectants to the required concentration, over several minutes/hours/days. The larger the crystal, the longer should be the incubation in each step.
- Small crystals often do better in terms of mosaicity increase than big crystals (often growth faults lead to end of crystal growth)
- use a synchrotron beam (as it is less divergent than the usual home source, and the apparent mosaicity is the sum of the crystal mosaicity and the crossfire)
- shoot at parts of the crystal to find if there are good and bad parts (this requires a small beam)