Synchrotron X-ray studies of biological preparations at low temperatures with optical monitoring of sample integrity

Increasing use of X-ray absorption spectroscopy (edge and EXAFS) to determine the local structure of active sites of biological molecules has caused greater interest in and attention to the nature of X-ray damage and the integrity of the sample. In a complementary way, efficient X-ray photon collection from the sample is required in order to maximize data acquisition and minimize sample damage. This report describes systems currently in use at Stanford Synchrotron Radiation Laboratory and Cornell High Energy Synchrotron Source, comprising two types of low-temperature techniques for sample protection and fast X-ray photon detection of large solid-angle collection.