FORMATION AND RELAXATION OF O-2(X-3-SIGMA(-)(G)) IN HIGH VIBRATIONAL LEVELS -LESS-THAN-OR-EQUAL-TO-V-LESS-THAN-OR-EQUAL-TO-23) IN THE PHOTOLYSIS OF O-3 AT 266 NM

Using pulsed laser photolysis (PLP) and laser-induced fluorescence (LI F) we have studied the formation of O-2(X-3 Sigma(g)(-)) in high vibra tional levels when O-3 is photolysed at 266 nm. Experiments have been performed in both Ar and N-2 diluents. In the former, O-2(X-3 Sigma(g) (-)) in high vibrational levels is formed primarily as a product of th e reaction between O(D-1) atoms and O-3:O(D-1) + O-3 --> 2 O-2(X-3 Sig ma(g)(-), v). In a large excess of N-2, the O(D-1) atoms are quenched and one only observes the O-2(X-3 Sigma(g)(-)) molecules by direct pho tolysis in the 'triplet channel': O-3 + hv (lambda = 266 nm) --> O-2(X -3 Sigma(g)(-), v) + O(P-3). Employing LIF in the (0, v) and (2, v) ba nds of the O-2 (B (3) Sigma(u)(-)-X-3 Sigma(g)(-)) system, we have cha racterised the nascent vibrational distributions from both these proce sses for 18 less than or equal to v less than or equal to 23. In addit ion, by observing how the population in specific vibrational levels ch anges with time, we have determined rate constants for vibrational rel axation of O-2(X-3 Sigma(g)(-), v = 21 and 22) with He, O-2, N-2, CO2, N2O and CH4. The results are compared with those obtained in other st udies for relaxation from the same and other levels of O-2(X-3 Sigma(g )(-)) and the implications of the results for atmospheric chemistry ar e discussed.