Development of a New Imaging-Plate Diffractometer (IPD-WAS) for Time-Resolved Crystallography with a Laboratory X-ray Source

A new imaging-plate diffractometer of the Weissenberg-camera type with an adjustable multilayer-line screen system (IPD-WAS) has been developed. Prior to data collection, the IPD-WAS automatically aligns the axis of a sample crystal and sets the multilayer-line (MLL) screens. The MLL-screen system is adaptable to a wide range of cell parameters of the sample crystals, and is advantageous for taking photographs in a wide rotation angle with a low background level. For Weissenberg photography, the IPD-WAS system uses two cylindrical imaging plates (IPs). The IPs are read two-dimensionally by rotary and transverse mechanisms. The rotary readout system has nonuniformity of response less than 1.4%, efficiency near 100% for Cu Kα radiation, a dynamic range of 1:10⁶ and spatial resolutions of 220 and 200 μm in the two directions. Owing to the good performance of the adjustable MLL screen system and the rotary readout system, the IPD-WAS achieves a data acquisition time of about l h with reflection data of sufficient quality (R_merge = 2.3% for a standard sample crystal), which is suitable for time-resolved X-ray crystallography. The IPD-WAS also enables faster crystal structure determinations of small molecules, including unstable crystals.