Selective Production and Kinetic Analysis of Singlet-state Metastable Molecular Nitrogen

研究了亚稳态分子氮的反应过程。用激光双光子激发基态氮分子产生N_2（a^1Πg）。通过N_2(a)态的碰撞弛豫可以产生邻近的N_2（a’^1Σu）态，用双光子激光诱导荧光技术鉴定了h (D)原子是这些亚稳氮分子与一些简单的氢化物（氘化物）化合物的产物。得到了以下结果：(1)N_2（a’）可被氢、甲烷和水分子有效失活，H原子的生成是N_2（a’）的主要出口通道之一。(2) N_2（a’）与CH_2D_2和HOD反应时，H和D原子的产率相同，说明反应是通过中间配合物进行的。(3)O_2和Xe有效地使N_2（a′）失活，生成三态分子氮，而在与N_2和ar的碰撞过程中，这种系统间交叉是低效的。此外，在Xe（6s[3/2]_1）到N_2（X ^1Σg^+）的能量传递过程中，有选择性地产生了N_2（B^3Πg）和N_2（W^3Δu）态。N_2整体猝灭的速率常数（B^3 Πg, υ=0）比N_2猝灭的速率常数（B^3 Πg, υ≧1）小一个数量级。以Xe（6s[3/2]_1,）与H_2（D_2）反应产生的H(D)原子数量为标准，揭示了H(D)原子的产生是N_2（B^3 Πg, υ=0）与H_2（D_2）反应中最重要的出口通道之一，而对N_2(a)的弛豫较小。这些结果不仅在基础科学领域，而且在等离子体技术等应用领域具有重要意义。

The reactive processes of metastable molecular nitrogen were investigated.N_2(a^1Πg) was produced by laser two-photon excitation of ground-state molecular nitrogen.The near-by N_2(a'^1Σu)state can be produced by collisional relaxation of this N_2(a)state.H(D) atoms were identified by a two-photon laser-induced fluorescence technique as products of these metastable nitrogen molecules with some simple hydride(deuteride)compounds.The following results were obtained.(1)N_2(a')can be deactivated efficiently by hydrogen, methane, and water molecules and the production of H atoms is one of the major exit channels.(2)In the reaction of N_2(a') with CH_2D_2 and HOD, the yields of H and D atoms are the same, implying that, the reaction proceeds via intermediate complexes.(3)O_2 and Xe deactivate N_2(a')efficiently to produce triplet-state molecular nitrogen, while such intersystem crossing is inefficient in the collisional processes with N_2 and Ar.In addition to these, it was revealed that N_2(B^3Πg)and N_2(W^3Δu)states are produced selectively in the energy transfer from Xe(6s[3/2]_1) to N_2(X ^1Σg^+).The rate constants for the overall quenching of N_2(B^3 Πg, υ=0)are one order of magnitude smaller than those for the quenching of N_2(B^3 Πg, υ≧1). By choosing the amount of H(D) atoms produced in the reaction of Xe(6s[3/2]_1,) with H_2(D_2) as a standard, it was revealed that the production of H(D) atoms is one of the most important exit channels in the reaction of N_2(B^3 Πg, υ=0) with H_2(D_2), while the relaxation to N_2(A)is minor.These results are important not only in the field of basic science but also in the applied fields such as plasma technology.