The direct determination of X-ray diffraction data from specific depths

Abstract

A direct method for determining powder diffraction data from a range of depths is described, where the linear absorption coefficient may vary with depth. A series of traditional data collections with varying angles of incidence are required, and the X-ray diffraction data arising from specific depths will be calculated by the transformation of these measured, angle-dependent spectra. These may then be analysed using any conventional method in order to gain information about characteristics of the sample in question at specific depths. Regularisation techniques have been used to solve the governing Fredholm integral equation to determine the depth-dependent diffractograms. The method has been validated by the use of simulated data having known model profiles, and has also been applied to experimental data from polycrystalline thin film samples.