Reactions of NH Radicals. II. Photolysis of HN3 in the Presence of C2H6 at 313 nm

Article abstract of DOI:10.1246/bcsj.56.2355

Photolysis of HN3 vapor with C2H6 was studied at 313 nm and 30 deg C.The products are N2, H2, CH4, NH4N3, CH3NH2 * HN3, C2H5NH2 * HN3, CH3N3, and CH3CN.The quantum yields of these products were measured as a function of pressures of HN3 and C2H6, and the light intensity.The following mechanism for the main reactions was proposed: HN3 + hv(313 nm) -> N2 + NH(a¹Δ); NH(a¹Δ) + HN3 -> 2N2 + 2H (2a); NH(a¹Δ) + HN3 -> NH2 + N3 (2b); NH(a¹Δ) + HN3 -> N2 + N2H2^* (2c); NH(a¹Δ) + C2H6 -> C2H5NH2^* (3); NH(a¹Δ) + C2H6 -> NH(X³Σ^-) + C2H6 (4); C2H5NH2^*-> CH3 + CH2NH2 (5); C2H5NH2^* -> CH3CN + 2H2 (6); C2H5NH2^* + M -> C2H5NH2 + M (7).The rate constant ratios at 30 deg C are: k₃/k₂ = 0.334; k₄/k₂ = 0.217; k₆/k₅ = 0.038.The values of k₇/k₅ for C2H6, HN3, CO2, and Xe are 36.5, 30.3, 29.0, and 14.5 dm³ mol^-1, respectively.The values of k₅ = 9.8 * 10⁹ s^-1, k₆ = 3.7 * 10⁸ s^-1, τ (half life of C2H5NH2^*) = 6.8 * 10^-11 s, η (collisional deactivation efficiency of C2H5NH2^*) = 1 for C2H6, HN3, and CO2, and η = 0.60 for Xe were obtained by using the collision theory.