AEROSOL FLUORESCENCE-SPECTRUM ANALYZER FOR RAPID MEASUREMENT OF SINGLE MICROMETER-SIZED AIRBORNE BIOLOGICAL PARTICLES

We report the operation of an aerosol analyzer capable of measuring th e fluorescence spectra of single micrometer-sized bioaerosol particles as they flow through the instrument. Particles entrained in an airstr eam initially traverse a cw, (continuous wave) (488 nm) ''trigger'' la ser beam where their elastic scattering and total fluorescence is meas ured with photomultipliers. When the elastic scattering and/or fluores cence signals exceed preset levels, a 266 nm UV ''probe'' laser is tri ggered to fire and illuminate preselected particles downstream from th e trigger laser. The UV laser-excited spectra of particles are measure d with the instrument's image-intensified CCD detector that is gated t o be on when the probe laser fires. We demonstrate the ability of the instrument to capture the fluorescence spectra of single micrometer-si zed airborne biological particles. Such spectra should be useful in di fferentiating between biological and nonbiological aerosols and in par tially characterizing airborne biological particles. (C) 1998 American Association for Aerosol Research.