15117-75-6Relevant articles and documents
Examination of the product channels in the reactions of NH(a 1Δ) with H2 and D2
Tezaki, Atsumu,Okada, Satoru,Matsui, Hiroyuki
, p. 3876 - 3883 (1993)
A flash photolysis study (193 nm) of HNCO has been conducted and the mechanisms of the reactions NH(a 1Δ) + H2 -> NH2 + H (1) and NH(a 1Δ) + D2 -> products (2) have been examined in detail at 295 +/- 3 K by monitoring NH(a 1Δ), H, D, NH2, and their D substituents via the laser induced fluorescence technique.From the pseudo-first-order analysis of the decay rate for NH(a 1Δ), rate constants have been determined as k1 = (3.96 +/- 0.17) x 10-12 and k2 = (2.62 +/- 0.08) x 10-12. (All the rate constants are expressed in units of cm3 molecule-1 s-1.) These rate constants are consistent with those determined from the time dependence of H and D atoms: they are k1 = (3.76 +/- 0.70) x 10-12 and k2 = (2.78 +/- 0.17) x 10-12.No pressure dependence has been observed for 10-100 Torr He.The branching fraction for H and D atoms as products for reaction (2) has been found to be / = 0.24/0.76, where D production is more abundant than statistically predicted.This indicates that reaction (2) is dominated by insertion of NH(a 1Δ) into the D2 bond, but vibrational energy of the reaction intermediate NHD2 is still localized in newly formed N-D bonds before it passes through the exit barrier into NHD + D or ND2 + H channels.NH2(X 2B1) was observed in (0,0,0) and (0,1.0) vibrational states as a product of reaction (1), and the observed time dependence of both vibrational states could be satisfactorily simulated by solving the master equation for vibrational relaxation of NH2.This analysis has indicated that the vibrational energy partitioning in the product NH2 is nearly statistical.
The four isotopomer reactions of NH(a) and ND(a) with NH3(X) and ND3(X)
Adam,Hack,Olzmann
, p. 439 - 455 (2007/10/03)
The reactions NH(a) + NH3 (X) → products (1) ND(a) + NH3 (X) → products (2) NH(a) + ND3 (X) → products (3) ND(a) + ND3 (X) → products (4) were studied in a quasi-static reaction cell at room temperature and pressures of 10 and 20 mbar with He as the main carrier gas. The electronically excited reactants NH(a) and ND(a) were generated by laser-flash photolysis of HN3 and DN3, respectively, at λ = 308 nm and detected by laser-induced fluorescence (LIF). Also the ground state species NH(X) and ND(X) as products were detected by LIF. From the measured concentration-time profiles of NH(a) and ND(a) under pseudo-first order conditions, the following rate constants were obtained: k1, = (9.1 ± 0.9) × 1013 cm3 mol-1 s-1 k2 = (9.6 ± 1.0) × 1013 cm3 mol-1 s-1 k3 = (8.0 ± 1.0) × 1013 cm3 mol-1 s-1 k4 = (7.2 ± 0.8) × 1013 cm3 mol-1 s-1. The major products are the corresponding NHi-D2-i(X) radicals (i = 0, 1, 2), whereas quenching processes such as NH(a) + ND3 → NH(X) + ND3 are of minor importance (1%). The isotope exchange NH(a) + ND3 → ND(X) + NHD2 is negligible, and the corresponding channel on the singlet surface NH(a) + ND3(X) → ND(a) + NHD2 (X) contributes with 1% to the overall NH(a) depletion in that reaction. The experimental findings are discussed in terms of a chemical activation mechanism by means of statistical rate theory.
