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In 1970s, Basbas et al.(Phys. Rev. A 1973, 7, 983; Phys. Rev. A 1978, 17, 1655) rose the possibility that PWBA ionisation crosssections could be expressed in terms of a universal ionisation cross-section. Starting from ECPSSR ionisation cross-sections and reproducing Basbas approach, a universal curve can be displayed against the reduced ion velocity, but data are too widespread to allow for a proper polynomial fit. In the present work, Basbas approach was revised and plotted against a rescaled, reduced ion velocity, eliminating most of the data spread and generating in practice a universal ionisation cross-section curve. In this revised approach, the screening parameter, θ n,o , assumes a major role in reaching the universal behaviour. Polynomial approximations are then made to the universal curves for incident H + and He 2+ ions. Cross-sections were then calculated using the polynomial approximations for target elements with atomic number from 11 to 92 and for ion beam energies from 50 keV to 10 MeV, for K-and L-shell ionisation cross-sections and are compared to experimental data from literature. Finally, X-ray yields were simulated for various thick target samples using these polynomial approximations and the outcomes are compared to data obtained at the ITN PIXE set-up.

Recently, a new PIXE code, LibCPIXE, was produced as a variant to the old DATTPIXE package following a simulation-based approach usually not used in PIXE data handling. This approach required to merge the PIXE data handling code, LibCPIXE to NDF, a well-known code for handling RBS and other IBA methods data, and showed that complex structures in the samples can dramatically change the observed PIXE yields. A full stepwise process was then undertaken in order to produce a new PIXE data handling code that uses the simulation approach not only to estimate the number of K-a and L-a x-rays emitted by the elements present in structured samples but to fit the entire PIXE energy spectra. This approach is of particular importance for the new high x-ray energy and high resolution PIXE set-up being installed at ITN, for the precise interpretation of PIXE spectra from complex targets, and also as a robust basis to relative yield ion energy dependence (RYIED) work discussed elsewhere in this conference. In this communication we present the fitting core for the new DT2 package and discuss its capacity.

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The characterization of thin films using PIXE, although basically a simple matter, in practice suffers from significant problems. Here two case studies are presented in which the use of grazing detection geometry is shown to be a good solution. The first case study, the analysis of GaSb-InAs films deposited on a GaSb substrate, relates to the measurement of elements of atomic number close to and below that of the substrate. Problems may be due to the tail of the peaks that correspond to x-rays emitted from the substrate, and also to the presence in the substrate of an element having large x-ray emission cross-sections. The use of the simulation capability implemented on the DATTPIXE package is shown to be of good help in the proper planning of the analysis procedure. In the second case study, the distinction between film contamination and substrate material contamination is discussed. In this case the characterization of a ZnO film deposited on sapphire is presented. The concept of equivalent depth is discussed and it is shown to be an important tool for a straightforward distinction between film and bulk contamination