COMPLEMENTARITY OF RBS, PIGE AND PIXE FOR THE DETERMINATION OF SURFACE-LAYERS OF THICKNESSES UP TO 30 MICRONS

The ratios of intensities of K X-rays of medium elements and L X-rays of heavy elements (whose energies lie from 5 to 25 keV) are particularly sensitive to changes in the geometrical parameters (direction of the incident beam and of the detector with respect to the sample surface), and may be used (possibly by comparison of results at different incident energies) to determine the composition of surface layers thicker than 10 μm. We will call this procedure thick layer PIXE (TL-PIXE). Proton backscattering is mainly used to appreciate the uniformity of the surface layer in the first 2-10 μm and is used here for the thickness calibration of samples studied by TL-PIXE. Resonant nuclear reactions giving rise to emission of characteristic γ-rays of light elements present in the backing are also used if the surface layer is too thick to allow the transmission of characteristics X-rays of elements in the substrate. We illustrate the potentiality of the method to measure thicknesses of gold on copper, zinc on iron, nickel on copper and aluminium-copper alloys. © 1990.