The influence of secondary fluorescence from elements adjacent to the microbeam spot on local concentration determination with PIXE

In position dependent PIXE analyses with microbeams secondary fluorescence may induce X-ray emission from elements in the micrometer-range vicinity of the beam focus spot. To study this effect in a simplified geometry, Cu-Au layer targets have been prepared. This material combination enables iterative electroplating for easy preparation of varying layer thickness with plane borders between the two materials and gives simultaneously sufficient secondary fluorescence. The proton beam spot of dimension 6 x 0.75 μm2 is swept across the polished end face of the layer sandwich and the Cu and Au X-ray intensities are measured as a function of the distance chi from the Cu-layer and of the proton energy Esub(p). (orig.)