Surface contamination by smearing during polishing – A PIXE study

Preparation of samples for PIXE analysis follows standard procedures in order to present a smooth, uniform surface for microscopic investigation and analysis. Reports on the quality of the surface preparation are scant. We report on investigations of preparation of metallic samples for micro-probe analysis. These samples are metal strips of typically 0.5 mm width and 10–15 mm length, sandwiched between natural pyrite crystals and quartz glass, mounted in epoxy resin. The surface was polished using diamond abrasives. The smearing of metallic Ag, Au and Cu was investigated and was found to be most prevalent for Cu, but also clearly detectable for Ag and Au. The potential influence of beam halo and beam scattering in the resin mount appears to be negligible, but the results imply additional, as yet unidentified, factors besides smearing to explain all observations.