Experimental X - ray production cross section ratios for ion beam materials analysis using MeV Heavy Ion PIXE

The widespread adoption of a heavy ion approach to Particle Induced X-ray Emission (PIXE) spectroscopy continues to remain attractive due to the inherently high sensitivity of the technique. This increased sensitivity comes as a result of relatively higher interaction cross sections compared to those induced by conventional light projectile ions, traditionally protons. Unfortunately, full implementation of Heavy Ion PIXE continues to be impeded by the unavailability of reliable ionization cross section data, fundamental to the quantitation of PIXE spectra. This also limits the adoption of a PIXE inclusive heavy ion induced Total Ion Beam Analysis (TIBA) approach to materials analyses, where synergies of multiple IBA techniques render a powerful tool capable of providing a consolidated description of material samples under analysis. The need for experimental cross section data for the validation of existing and developing new theoretical frameworks thus continues to exist. This presentation describes an empirical approach to the approximation of heavy ion induced X-ray production cross sections, through systematic parameterization of experimental proton – heavy ion cross section ratios. The cross section ratios have been calculated for select heavy ion projectiles in metallic thin films measured within the 0.2 MeV/u – 1.0 MeV/u ion velocity range. Measured cross sections are finally compared to approximations by the semi-empirical model developed and the conventional ECPSSR theory, where agreements and discrepancies are discussed in terms of the dominant ionization mechanisms.