Diffraction apparatus for X-ray diffraction imaging

To visualize the structures of frozen-hydrated non-crystalline biological particles such as cells and organelles, two types of diffraction apparatus were developed for X-ray diffraction imaging (XDI) experiments at cryogenic temperatures using synchrotron X-rays and X-ray free electron laser (XFEL) pulses. Cryogenic experiments are advantageous for the suppression of the radiation damage of specimens over the long exposure times in synchrotron experiments. In addition, frozen-hydrated biological specimens are free from dehydration and bubbling under vacuum conditions at ambient temperature. One apparatus, KOTOBUKI-1, is dedicated to cryogenic XDI experiments at the synchrotron radiation facility SPring-8. Another apparatus, named TAKASAGO-6, was developed for cryogenic XFEL-XDI experiments at SACLA. Each apparatus is equipped with a cryogenic pot mounted on a goniometer stage for the collection of diffraction data at 66–80 K. The details of the devices used in these apparatuses are introduced together with the miscellaneous devices assisting their practical use. This chapter provides examples and clues to construct a new diffraction apparatus for diffraction experiments at cryogenic temperatures, including the delivery of cooled specimens.