ON THE COLLECTION OF DIFFRACTION DATA SIMULTANEOUSLY OVER A RANGE OF ENERGY

We report on using energy-dispersive focusing optics for the simultane ous collection of single crystal diffraction data over a continuous en ergy range. A horizontal diffraction, bent-crystal monochromater which is made to focus inside the Rowland Circle can produce a small focal spot containing a wide energy bandpass. The energy dispersion of the c onvergent beam can be adjusted to excite Bragg reflection, over a broa d energy range, in a crystal placed at the focus. The resultant diffra ction pattern is then collected using a position-sensitive detector. W e describe a method for adjusting the optical parameters of the monoch romator to match its output to a range of d-spacing in the sample. We illustrate the technique by studying a reflection in germanium in an e nergy range around the K-edge at 11.1 keV. This method may prove usefu l for anomalous diffraction from small samples, in the scattering of c ircular-polarized X rays, and in studies of the diffraction fine struc ture above absorption edges.