PNNL

Abstract

Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersed x-ray analysis. With moving substrates one can achieve time resolution of seconds to minutes. We demonstrate how to increase the time resolution to a few milliseconds to provide real-time information in this paper. Our fast time-resolved aerosol collector (“Fast-TRAC”) microscopically observes the particle collection on substrate and record an on-line video. Particle arrivals are resolved to within a single frame (17 to 4 ms in this setup), and the spatial locations are matched to the subsequent single particle analysis. This approach provides real-time information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and long term site monitoring.