Single-shot fluorescence spectra of individual micrometer-sized bioaerosols illuminated by a 351- or a 266-nm ultraviolet laser

Abstract

Reproducible fluorescence spectra of individual 2- to 5-microm -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.

Performance assessment of UVAPS: Influence of fungal spore age and air exposure

“…The first group includes trials and studies to design and test an instrument capable of differentiating between biological and non biological aerosols such as a Fluorescence Spectrum Analyser and an Ultraviolet Aerodynamic Particle Sizer (UVAPS) (Brosseau et al, 2000;Chen et al, 1996;Hariston et al, 1997;Hill et al, 1995;Ho et al, 1999;Kaye et al, 2000;Nachman et al, 1996;Pan et al, 2003;Pinnick et al, 1998;Pinnick et al, 1995). The second group of studies aimed at designing and testing an instrument with the capability to characterise particle composition in order to discriminate between the bioaerosols themselves (Cheng et al, 1999;Pan et al, 1999;Seaver et al, 1999;Sivaprakasam et al, 2004;Weichert et al, 2002). Some of these studies used multiple UV excitation wavelength to create more than one fluorescence spectra for each species under investigation (Cheng et al, 1999;Sivaprakasam et al, 2004).…”

Desorption/Ionization Fluence Thresholds and Improved Mass Spectral Consistency Measured Using a Flattop Laser Profile in the Bioaerosol Mass Spectrometry of Single Bacillus Endospores

“…They are also relevant to other types of instruments. Several bioaerosol detectors measure UV fluorescence from biological particles [14][15][16][17][18][19] . More intense UV excitation generally leads to more intense fluorescence 20 , which is beneficial, but if the excitation is too intense the aerosol particles will be damaged potentially interfering with more selective methods of subsequent analysis.…”

Technical Note: Organics-Induced Fluorescence in Raman Studies of Sulfuric Acid Aerosols

“…Hence the usage of Raman spectroscopy in eld experiments aiming at an identi cation of the compositions of ambient aerosols has to be carefully evaluated, since uorescence may govern the spectra. On the other hand, uorescence spectroscopy has been used in laboratory experiments to identify biogenic material in water droplets (Pan et al 1999;Kaye et al 2000). This is an attractive experimental possibility because of its low detection limit.…”