Kinetics of aerosol formation during tungsten hexacarbonyl photolysis

The kinetics of formation and growth of the nanometer-sized aerosol particl es during tungsten hexacarbonyl (W(CO)(6)) vapour photolysis in air have be en investigated. Special attention has been given to the research on the in fluence of coagulation during the time interval (t(1)) between the moment t he vapours leave the irradiation zone (i.e, generation of condensing produc ts stops) and the moment particle concentration and size distribution are m easured, Aerosol formation kinetics within the Smoluchowski coagulation mod el in the clusters free-molecular collision regime was modelled numerically . The rate of monomer formation F(t) was calculated for different rates of W(CO)(6) photolysis at various t(1) values. Calculated values of F(t) were in good agreement with measured W(CO)(6) photolysis rates W-phot. Particles concentration and size were shown to be determined by irradiation dose D = I/I-0 x t(0) (I/I-0 is relative irradiation intensity, t(0) is irradiation time), when t(1) >> t(0). (C) 2000 Elsevier Science Ltd. All rights reserv ed.