In this publication we give an exhaustive account of photochemical aerosol
formation from acetaldehyde. Rate constants for photolysis are measured, an
d the kinetics of photonucleation is studied in argon and air hows. The rat
es of formation and quantum yields of aerosols are assessed by comparing th
e results of model calculations with experiment. A chemical mechanism of th
e process is ascertained through identification of free radicals, gas-phase
products, and resulting aerosols.