Processing of X-ray diffraction data from partially oriented specimens

A numerical deconvolution procedure has been developed to measure X-ray diffraction data from partially oriented specimens to the highest possible resolution. The resolution to which X-ray data from non-crystalline specimens can be measured is limited by the disorientation of the particles in the specimen. The distribution of particle orientations causes the X-ray reflections to be smeared into arcs about the center of the diffraction pattern. At sufficiently high diffraction angles, this arcing results in the overlap of adjacent reflections. Conventional methods of densitometry used to measure intensities from X-ray films cannot be used in this region. By measuring all the optical densities on an X-ray film and placing them on a polar grid, an angular deconvolution can be performed to correct for the disorientation and separate the intensities from overlapping reflections. This calculation results in a determination of the X-ray intensities and background, and a quantitative measurement of the highest possible resolution to which the data can be reliably measured. X-ray data from partially oriented specimens of several macromolecular aggregates have been collected with this method.