KOTOBUKI-1 apparatus for cryogenic coherent X-ray diffraction imaging

Abstract

We have developed an experimental apparatus named KOTOBUKI-1 for use in coherent X-ray diffraction imaging experiments of frozen-hydrated non-crystalline particles at cryogenic temperature. For cryogenic specimen stage with small positional fluctuation for a long exposure time of more than several minutes, we here use a cryogenic pot cooled by the evaporation cooling effect for liquid nitrogen. In addition, a loading device is developed to bring specimens stored in liquid nitrogen to the specimen stage in vacuum. The apparatus allows diffraction data collection for frozen-hydrated specimens at 66 K with a positional fluctuation of less than 0.4 μm and provides an experimental environment to easily exchange specimens from liquid nitrogen storage to the specimen stage. The apparatus was developed and utilized in diffraction data collection of non-crystalline particles with dimensions of μm from material and biological sciences, such as metal colloid particles and chloroplast, at BL29XU of SPring-8. Recently, it has been applied for single-shot diffraction data collection of non-crystalline particles with dimensions of sub-μm using X-ray free electron laser at BL3 of SACLA.

Signal enhancement and Patterson-search phasing for high-spatial-resolution coherent X-ray diffraction imaging of biological objects

“…1b and Table 1). Under the experimental conditions of CXDI at SACLA11 (Supplementary Table 1), a diffraction pattern with photon counting noises (Poisson noises), after removing central data (25 × 25 pixels; ≤ S low = 1.7 μm −1 ) blocked by the beamstop (Fig. 1a), was calculated from the model, and gave signals up to a resolution of ~25 nm ( S = ~40 μm −1 ).…”

“…X-ray free-electron laser (XFEL) sources launched recently67 have the potential to solve this contrary problem, since the femto-second pulse duration and the high photon flux density of XFELs allow diffraction data collection before sample destruction8. Thus far, XFEL-CXDI has visualized a large virus9 and a macromolecular assembly10, an organelle11 and a bacterium12 at resolutions of 30–60 nm. However, the small scattering cross-section of biological samples remains a big obstacle to extending the resolution of electron density maps with the currently available photon flux density of XFELs.…”

“…We first demonstrate the feasibility of the method based on calculations derived from CXDI experiments at the Japanese XFEL facility, SACLA11. Then, we discuss the potential and limitations of the method in practical applications.…”

Development of an X-ray pixel detector with multi-port charge-coupled device for X-ray free-electron laser experiments

“…In the case of coherent X-ray imaging applications with a 5-7 keV XFEL beam, these camera heads were directly connected to the vacuum chamber. 27 In other applications such as serial femtosecond crystallography, and quantum optics experiments, the camera head chamber was sealed by a beryllium window. All the single-, dual-, and octal-sensor detectors share a common cooling mechanism.…”

“…Data are taken by upstream octal-sensor detector and downstream dual-sensor detector 27. The calibrated data of the two detectors is shown (a).…”