Physical and chemical (Raman) characterization of bioaerosols - Pollen

The chemical characterization of pollen is explored using fluorescence spec troscopy and two Raman spectroscopic techniques. The on-line Raman techniqu e involves trapping single pollen particles in an electrodynamic balance co upled to a Raman spectrometer. The off-line method requires the pollen samp les to be deposited on a substrate and analyzed using a Raman microprobe. I t is shown that fluorescence spectra of various grass and tree pollens do n ot show sufficient differences to provide an adequate method for characteri zing them. Furthermore, the strong fluorescence masks any underlying Raman spectra. Although photochemical bleaching can reduce the fluorescence signa l, it is shown that use of a near-IR laser provides Raman signals that can be used to characterize the pollen particles. In the on-line system, the pa rticle density was determined From electrodynamic springpoint measurements and the geometric pollen size measured with a video microscope. (C) 2000 El sevier Science Ltd. All rights reserved.