Concentration profile determination by pixe analysis utilizing the variation of beam energy

The problem of depth profiling with PIXE is formulated as an explicit convolution integral, and the deconvolution algorithms previously used in the literature are reviewed. The best of them, up to now, which consists of an iterative procedure associated with data smoothing at each step of the iteration, is generalized and analyzed in detail. Starting from published cross sections for X-ray production, X-ray absorption coefficient and energy-range correspondence, it is shown that this procedure is able to reproduce nicely the flat profile of a homogeneous Ag-3 at.% Zn alloy as well as the erf-like profile of Zn depletion in the same alloy after an annealing treatment under vacuum. The emphasis is put on the sensitivity of the method and on how straining conditions can improve it.

Evaluation of depth profiling with PIXE

Using proton-induced X-rays to determine three parameters of the depth profile of foreign atoms in bulk material

A method of determining the depth of impurities by proton-induced X-rays

Possible advantages of low energy proton beams employed for PIXE analysis in materials research are discussed qualitatively in comparison with beams of a few MeV energy. In general, proton energies below 1 MeV seem to be favourable for the detection of light impurities in heavy matrices and for the analysis of near-surface regions. Some examples of PIXE analysis using the proton beam from a 350 kV ion accelerator are presented concerning impurity contaminations in Au, depth profiling at layer structures of Pt and Bi, and surface layers formed by chemical reactions on W.

Specific applications of a 350 kv ion accelerator for PIXE analysis of solid state samples

We attempt to determine the target composition of one homogeneous layer of foreign atoms in bulk material by comparing the yields for proton‐induced x rays at two different energies The problem is formulated mathematically and an approximate method of solution is given The method uses a calibration curve which is given by the ratio of the yields at the two energies for a pure foil of the foreign material of known surface density Both thickness and location in depth of the foreign layer can be determined The method is applied to sandwich targets (Ag‐Cu‐Ag and Ge‐Cu‐Ge) of known layer thickness (determined by Rutherford backscattering) By measuring the same target under various conditions, and by comparison to backscattering, it is shown that a mean depth of Cu atoms of about 1 mg/cm2 can be measured to an accuracy of about 4%

O. Benka

Papers

Determination of the depth of impurity atoms in bulk material by proton-induced x rays