Nuclear microprobe analysis of atmospheric aerosol samples: Comparison with bulk measurements and analyses of individual particles

Selected aerosol filter samples, which have been analyzed by bulk analysis techniques, were examined with the Oxford scanning proton microprobe using micro-PIXE and micro-RBS. From a comparison of the micro-PIXE data for large collections of particles with the bulk analysis results, it was estimated that micro-PIXE of aerosols provides data which is accurate to within 10-20%. Loss in the course of the microprobe bombardment was examined for the elements detected by PIXE, but was generally insignificant. Examples of analyses on complex particle agglomerates are presented. For individual calcareous aerosol particles from Israel, the contributing chemical compounds were identified and quantitatively determined. Several of these particles consisted of a single compound (e.g., calcium carbonate, calcium sulphate), but mixed particles with equal molar amounts of two compounds (e.g., of calcium carbonate and calcium phosphate) were also observed. It is also indicated what further improvements in nuclear microprobe analysis are especially desirable for examinations on submicrometer sized aerosol particles. (C) 1997 Elsevier Science B.V.