Three-dimensional imaging of aerosol particles with scanning proton microprobe in a confocal arrangement

Abstract

We have reconstructed three-dimensional (3D) element-specific distributions of aerosol microparticles captured in a thick quartz filter. The characteristic x rays were induced by a proton microprobe and detected by a Si(Li) spectrometer equipped with a polycapillary lens. Combining a fine microbeam scanning in the lateral plane with the sample movement parallel to the beam axis, the aerosol particles were driven across the sensitive microvolume and for Fe, Ca, S, and Si a sequence of two-dimensional lateral x-ray images was recorded. This is the first example of an x-ray element selective 3D imaging of a few micrometer sized objects with a proton beam.