INVESTIGATION OF A MODIFIED SINCLAIR-LA MER AEROSOL GENERATOR IN THE SUBMICROMETER RANGE

A systematic study of the aerosol output was conducted from a modified commercially available Sinclair-La Mer-type monodisperse generator (T SI 3475) in the submicrometer region. The generator produces three dif ferent types of aerosols: sodium chloride, DEHS droplets condensed on NaCl nuclei and homogeneously nucleated DEHS droplets. The first two w ere found io be unimodal while the last one had a bimodal distribution . The aerosol droplet size distribution of the condensed aerosols was measured as a function of nuclei concentration, saturator temperature and saturator flow. It was concluded that when nuclei concentration de creases below similar to 10(6) cm(-3) homogeneous condensation is no l onger suppressed and coexistence of two kinds of aerosol droplets of d ifferent size can be observed. The size distribution of all generated aerosols was measured by a scanning mobility particle sizer (SMPS). (C ) 1998 Elsevier Science Ltd. All rights reserved.