Reactions of N2(a′ 1Σu−) with H2, CH4, and their isotopic variants: Rate constants and the production yields of H(D) atoms

The reactions of N2(a′ 1Σu−, v=0) with H2, CH4, and their isotopic variants were examined. N2(a′, v=0) was produced by energy transfer from N2(a 1Πg, v=0), while N2(a, v=0) was produced by two-photon excitation of ground state N2. The rate constant for the deactivation of N2(a′,v=0) can be determined by measuring the decay profiles of N2(a, v=0) under the conditions that equilibration between N2(a, v=0) and N2(a′, v=0) can be assumed. The detection of N2(a, v=0) was accomplished by a laser-induced fluorescence technique by utilizing the N2(b′ 1Σu+, v=7) state as an upper state. The rate constants for the quenching of N2(a′, v=0) by N2, H2, D2, CH4, CH2D2, and CD4 were determined to be (2.0±0.1)×10−13, (2.8±0.1)×10−11, (1.7±0.1)×10−11, (2.9±0.2)×10−10, (2.4±0.3)×10−10, and (2.6±0.2)×10−10 cm3 molecule−1 s−1, respectively. H(D) atoms were identified as reaction products by a two-photon laser-induced fluorescence technique. The yields for the production of H(D) atoms from CH4 and CD4 were both determined to be 0.7±0.2 under the assumption that the only exit for H2(D2) is the production of two H(D) atoms. No preferential production of H or D atoms was observed in the reaction with CH2D2, suggesting that the reaction proceeds via bound intermediate complexes.