Vol. 15, issue 05-06, article # 19

Abstract:

A new experimental technique has been developed for direct time-resolved studies of the kinetics of aerosol formation. It is based on a combination of pulsed excimer laser photolysis and space- and time-resolved monitoring of scattered light with a gated intensified CCD camera. The experimental setup allowed detection of aerosol particles more than 45-50 nm in diameter and with the number concentration ranging from 3 10⁶ to 6 10⁸ particles/cm³. The time range of aerosol formation kinetics was from 10^-7 to 10^-2 s. Kinetics of photochemically induced aerosol formation in 1.4-cyclohexadiene-NO-air mixture was studied. The evolution of the particle number concentration and the size distribution was investigated, as well as the increase in the scattered light intensity depending on a delay after the photolyzing pulse. Quantum yield of aerosol products was estimated to be in the range from 10^-2 to 2%, which is comparable with the values characteristic of organic aerosols.