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Single-Shot Fluorescence Spectra of Individual Micrometer-Sized Bioaerosols Illuminated by a 351- or a 266-nm Ultraviolet Laser
YALE UNIV NEW HAVEN CT DEPT OF APPLIED PHYSICS
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Reproducible fluorescence spectra of individual 2 to 5 micrometers diameter biological aerosol particles excited with a single shot from a Q-switched laser 266 or 351 nm have been obtained with highly improved signal-to- noise ratios. Critical to the advance are crossed diode-laser trigger beams, which precisely define the sample volume, and a reflecting objective, which minimizes chromatic aberration and has a large N.A. for collecting fluorescence. Several allergens red oak, meadow oat pollen, paper mulberry pollen, and puffball spores have different fluorescence spectra. Bacillus subtilis fluorescence spectrum deteriorates at high 266-nm incident intensity. Dry riboflavin particles illuminated with a 351-nm light exhibit a new 420-nm fluorescence peak that grows nonlinearly with laser pulse energy.
APPROVED FOR PUBLIC RELEASE