QUANTUM YIELD OF NO3 FROM PEROXYACETYL NITRATE PHOTOLYSIS

Peroxyacetyl nitrate (PAN) vapor was photolyzed at 248 nm and the NO3 photoproduct was detected by laser-induced fluorescence. The quantum y ield for the production of NO3 was determined by comparison to N2O5 ph otolysis data taken under identical experimental conditions, Contribut ions to the observed laser induced fluorescence were found to arise fr om excited-stare photoproducts such as NO2. The excited-state fluores cence contributions were investigated, and a data analysis methodology was established to minimize their effects. The average of data collec ted over a range of total pressures, precursor concentrations, and buf fer gases was 0.3 +/- 0.1 for the NO3 quantum yield, where the quoted statistical uncertainty represents two standard deviations. This resul t, combined with our previously reported value of 0.83 +/- 0.09 for th e NO2 quantum yield from the photolysis of PAN, suggests that NO2 and NO3 represent the only nitrogen-containing products in the 248 nm phot olysis of PAN. The atmospheric implications of a NO3 producing channel in PAN photolysis are considered.