Application of mu Raman Microscopy to the Identification of Individual Airborne Particles: Preliminary Results from Kozani's Area, Northern Greece

In the present study, Raman spectroscopy combined with a con-focal microscope has been applied for the identification of airborne particulate matter collected from Kozani's area, northern Greece. This technique provided a rapid and accurate identification of the molecular composition of micrometer sized (down to 2 mu m) airborne particles. Different experimental conditions (laser excitation wavelength of 532 and 780nm, slit and pinhole aperture, 50x and 100x objectives, number of exposures, and time of each exposure) were employed in order to obtain the optimal analytical parameters. The slit aperture and the 532nm laser source were preferable. Removal of the background interference caused by the blank Teflon filter was performed for the acquisition of Raman spectra of minute (<10 mu m) airborne particles, whereas no background correction was necessary for larger particles (>10 mu m). Several distinct mineral phases were determined, such as: the common geogenic minerals calcite, gypsum, anhydrite, titanium oxides and microcline (feldspar); the anthropogenic minerals, black carbon and nitrates; and the lepidolite and smectite (phyllosilicates) attributable to Saharan dust episodes.