Overall rate constants for the removal of N2(A,v) by O2 and O were measured at 298 K in a rapidly pumped flow reactor using laser-induced fluorescence (LIF) detection of N2(A,v) by excitation in the first positive system of N2, B(3πg)←A(3Σ+u). O atoms were generated in microwave discharges of pure O2 prepared by thermal decomposition of KMnO4. Measured rate constants for N2(A,v)+O2 increased from 2.5×10−12(v=0) to 5.7×10−12 cm3 s−1(v=3). For N2(A,v)+O(3P), they were an order of magnitude larger, rising from 3.5×10−11(v=(0) to 5.2×10−11 cm3 s−1(v=3). They are compared with previous work and discussed in terms of the likely molecular interaction that they represent.

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The line absorption technique was applied to the kinetic study of the two metastable atomic nitrogen states N (22D) and N (22P) in a flowing afterglow system. The optical absorptions of the NI 1493-Å (2p32D−3s2P) and 1743-Å (2p32D−3s2P) transitions were used for the quantitative measurement of N (22D) and N (22P) concentrations. Deactivation of N (2D) and N (2P) by the Pyrex tube wall was found to be very efficient, i.e., occurs at nearly every collision. The second-order rate constants at 300°K for the removal of N (2D) by O2, N2O, CO2, NO, N2, Ar, and He were found to be (6±2)×10−12, (3.5±1.2)×10−12, (5±2)×10−13, (7±2.5)×10−11, (1.6±0.7)×10−14, (1±0.6)×10−16, and ≤ 1.6×10−16 cm3 sec−1, respectively. It was established that the process for the first three reactant gases results in chemical reaction rather than physical quenching.

Rate constants for the reactions H02 + O (1) and H02 + H (2) were measured in a discharge-flow apparatus fitted with back-to-back laser-induced fluorescence and vacuum UV resonance fluorescence detectors. The decays of [O] and [H] were monitored under conditions of large excess H02, generated by F + H202 and detected as OH after conversion with added excess NO. kl and k2 were found to be (5.4 ± 0.9) X 10"11 and (7.4 ± 1.2) X 10~n cm1 23 s'1, respectively. The branching ratios of (2), whose three sets of products are OH + OH (2a), H20 + O (2b), and H2 + 02 (2c) were determined by reacting small, known concentrations of H02 with large excess of H and measuring the [OH] and [0] formed. They were found to be 0.87 ± 0.04, 0.04 ± 0.02, and 0.09 ± 0.045, respectively. These results are compared with published data and discussed in terms of the likely course of the molecular interactions.

The rate constant for the reaction C1+ CH, 1 , CH3 + HCl has been determined over the temperature range of 200"-500"K using a discharge flow system with resonance fluorescence detection of atomic chlorine under conditions of large excess CH4. For 300" > 7' > 200°K the data are best fitted to the expression kl = (8.Curvature is observed in the Arrhenius plot such that the effective activation energy increases from 2.6 kcal/mol at 200" < T < 300°K to 3.5 kcal/mol at 360" < T < 500°K. The data over the entire range may be fitted by the expression k l = 8.6 X T2." exp[-795/T]. These results are compared with other experimental studies and with a semiempirical transition state calculation. Their atmospheric significance is discussed.