QUENCHING OF NH(A1-DELTA,UPSILON''=1,2) AFTER HN3 KRF-LASER PHOTOLYSIS

The photolysis of HN3(X approximately), HN3(X approximately 1A') + h-nu --> NH(a1-DELTA,upsilon") + N2(X1-SIGMA-g+), at lambda = 248 nm was studied in a quasistatic laser photolysis LIF cell. NH(a1-DELTA) with upsilon" = 0-3 was detected directly by the c(1PI,upsilon' = 0) <-- a(1-DELTA,upsilon") excitation spectra. The transitions c(1-PI,upsilon' = 1) <-- a(1-DELTA,upsilon" = 0-3) were also detected. The initial concentrations of NH(a1-DELTA,upsilon" = 0-3) after single-photon photolysis were determined as [NH(a,upsilon" = 0)]/[NH(a)] = 0.32, [NH(a,upsilon" = 1)]/[NH(a)] = 0.47, [NH(a,upsilon" = 2)]/[NH(a)] = 0.17, and [NH(a,upsilon" = 3)]/[NH(a)] = 0.038. The deactivation rate constant for NH(a,upsilon" = 1) + N2 --> prod. was found to be kappa-1 = (1.7 +/- 0.2) x 10(11) cm3/(mol s) and the value kappa-2 = (1.7 +/- 0.2) x 10(11) cm3/(mol s) was measured for the rate constant of the reaction NH(a,upsilon" = 2) + N2 --> prod. The equivalent quenching rates for HN3, instead of N2, were determined to be kappa-3 = (7.6 +/- 0.8) x 10(13) cm3/(mol s) and kappa-4 = (7.0 +/- 0.8) x 10(13) cm3/(mol s), respectively. For He as a quenching gas, deactivation rates kappa = (5.2 +/- 1) x 10(8) cm3/(mol s) were obtained for upsilon" = 1 and kappa = (6.2 +/- 1) x 10(8) cm3/(mol s) for upsilon" = 2.