The UV-excited fluorescence spectra of individual flowing biological aerosol particles as small as 2 pm in diameter have been measured in real time (rates up to 10 particles per second). The particles are illuminated with a single shot from a Q-switched 266- or 351-nm laser. The signal-to-noise ratio and resolution of the spectra are sufficient for observing small line-shape differences among various types of bioaerosols (e.g., bacteria versus pollens) and ...
Improved real-time methods for characterizing airborne biological particles are needed. Here we review our efforts in developing techniques for measuring the laser-induced fluorescence (total and spectrally dispersed) of individual airborne particles, and describe our present system, which can measure fluorescence spectra or single micrometer-sized bioaerosol particles with good signal-to-noise ratios. We demonstrate the capability of this system by showing measured spectra of a variety of airborne particles generated in the ...
We report the operation of an aerosol analyzer capable of measuring the fluorescence spectra of single micrometer-sized bioaerosol particles as they flow through the instrument. Particles entrained in an air stream initially traverse a cw (488-nm) "trigger" laser beam, where their elastic scattering and total fluorescence are measured with photomultipliers. When the elastic scattering and/or fluorescence signals exceed preset levels, a 266-nm UV "probe" laser is triggered to fire and ...
In this report, the equations which describe the attenuation of long- wavelength electromagnetic radiation by water fogs and rain are briefly reviewed and explained under the assumption that the aerosol droplets are spherical and that the irradiance of the beam is in the "linear" regime. Calculations of water fog attenuation coefficients are made using the Rayleigh approximation, and an approximate error analysis of this approximation is made by comparing Rayleigh ...
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