Measurement of fluorescence spectra from atmospheric single submicron particle using laser-induced fluorescence technique

This paper describes the development of an instrument for online detection of certain types of organic aerosol particles in the atmosphere using the laser-induced fluorescence (LIF) technique. Aerosol particles, sampled from the atmosphere to an optical chamber, is first detected by scattering of a 635-nm continuous wave (CW) laser beam and then excited by a 266-nm pulsed laser, to induce fluorescence emission. The fluorescence in the 300–600 nm wavelength range is spectrally dispersed by a grating spectrometer and then detected by a 32-anode photomultiplier tube (PMT). The performance of the instrument was tested using laboratory-generated particles with known fluorescence properties. We found that pure tryptophan particle as small as 0.3 μm was detectable with fluorescence. Preliminary results from ambient measurements and cluster analysis are presented and the interpretation of the classification is discussed.