A method for the determination of atomic displacements in compound crystals by means of RBS-PIXE-channeling experiments

Abstract

A method which combines proton-induced X-ray emission (PIXE), Rutherford backscattering (RBS) and ion channeling, which enables the determination of static or dynamic root-mean-square displacements of constituent atoms in compound crystals is described. Full PIXE and RBS channeling angular scan curves are measured simultaneously by scanning through a major axis of the crystal under study. The experimental data are interpreted by using two different methods: A) a simple semi-analytical model which takes advantage of the depth information contained in RBS spectra to estimate depth correction factors needed to analyze the PIXE angular scan data, and B) a Monte Carlo simulation program of channeling, which takes into account the special structural features of the materials studied and allows for a direct comparison of simulated results with experimental PIXE data. The use of the technique is demonstrated by deducing rms displacements of constituent atoms of some II–VI (binary and ternary) semiconductors analyzed by both methods. The present results agree well with vibrational amplitude data obtained from X-ray diffraction measurements available from the literature.