Multiple UV wavelength excitation and fluorescence of bioaerosols.

A two-wavelength laser-induced fluorescence technique is described for detecting and classifying biological aerosols. Single aerosols, smaller than 10 mm, are interrogated with 266 nm and 355 nm laser pulses separated in time by 400 ns. Fluorescence signals excited by these pulses are detected in three broad spectral bands centered at 350 nm, 450 nm and 550 nm. The results indicate that bacterial spores, vegetative bacterial cells and proteins can be differentiated based on the two wavelength excitation approach. Estimates of the fluorescence cross sections for 16 bioaerosol simulants and interferents are presented.