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 anal ysis techniques, were examined with the Oxford scanning proton micropr obe using micro-PIXE and micro-RBS. From a comparison of the micro-PIX E data for large collections of particles with the bulk analysis resul ts, it was estimated that micro-PIXE of aerosols provides data which i s accurate to within 10-20%. Loss in the course of the microprobe bomb ardment was examined for the elements detected by PIXE, but was genera lly insignificant. Examples of analyses on complex particle agglomerat es are presented. For individual calcareous aerosol particles from Isr ael, the contributing chemical compounds were identified and quantitat ively determined. Several of these particles consisted of a single com pound (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 des irable for examinations on submicrometer sized aerosol particles. (C) 1997 Elsevier Science B.V.