Use of the polychromatic Laue method for short-exposure X-ray diffraction data acquisition

The polychromatic Laue method was developed for application in flash X-ray diffraction studies; it can also serve as a valuable tool for fast data acquisition with conventional X-ray and synchrotron sources. The present method was developed with a sealed X-ray tube (Mo anode, 45 kV, 20 mA) and a crystal of known structure for calibration of the source spectrum. The resulting experimental energy distribution of the source has been successfully approximated in the range 0.45-1.9Å, by an analytical expression based on a theoretical curve for white radiation. The problem of coincidence of several harmonics in a single diffraction spot has been partially solved by the multiple-film technique. The efficiency of the method was tested on a crystal of (2-tert-butyloxycarbonyl)-9-oxo-6-oxa-l-azabicyclo[5.2.0]nonane, which was also investigated by means of a conventional four-circle X-ray diffractometer. The comparison of about 500 structure factors derived by the two methods yielded an R factor of 0.065. Data acquisition by the Laue method is about two orders of magnitude faster.