A theoretical study of the NH+NO reaction

Abstract

A threedimensional quantum mechanical study of the NH+NO reactionsWe present a quasiclassical trajectory study of the NHϩNO reaction using a global potential energy surface that is capable of describing branching to the HϩN 2 O and OHϩN 2 products after initial formation of a HNNO intermediate complex. The surface is based on a many-body expansion wherein fragment potentials for the species N 2 H, HNO, and N 2 O are incorporated, using either previously developed potentials, or in the case of N 2 O, a newly developed potential. The three-body parts of these fragment potentials are damped in the four-body region to provide a zeroth order four-body surface, and then additional four-body terms and mapping transformations are applied to make the final four-body potential match the results of ab initio calculations for eight important HNNO stationary points ͑minima and saddle points͒ and for several reaction paths. In addition to this ''best fit'' surface ͑surface I͒, a second surface ͑surface II͒ is developed in which the ordering of the saddle points leading to formation of HϩN 2 O and OHϩN 2 is reversed, and the energy release during 1,3 hydrogen migration is modified so that the N-N stretch experiences smaller distortions from N 2 equilibrium during the reaction leading to OHϩN 2 . Quasiclassical trajectory results on surface I show generally good correspondence with experiment, with a branching fraction of 13Ϯ3% for the formation of OHϩN 2 at 300 K, and relatively low OH and N 2 vibration/rotation excitation. The results on surface II are similar with respect to both branching and energy partitioning, indicating relatively weak sensitivity of the results of key features of the surface.

Combustion Chemistry of Nitrogen

“…As discussed in the text, the isomerization barrier between HNNO and NNOH would need to be significantly lower to have N2 + OH dominate at lower temperature. Bradley et al (1995), who report a branching fraction of 13 ± 3% for the N2 + OH channel and show that decreasing the isomerization barrier by 40 kllmol increases the branching fraction by less than a factor of two. An additional feature of interest in Fig.…”

Mechanism of the Vanadium Oxide-Catalyzed Selective Reduction of NO by NH3. A Quantum Chemical Modeling

“…Theoretical studies of the thermal deNO x process [21][22][23][24][25][26][27][28] suggest the reaction of NH 2 with NO to be a primary product channel leading to N 2 and H 2 O, where NH 2 NO has been considered to be a crucial intermediate. The secondary products from this channel seem to be N 2 H + OH, 21,23,24,28 which act as the chain-branching step allowing the process to proceed.…”

Ultrafast OH production in clusters containing N2O and HI

“…This was the original goal of the present study. The buildup time of р100 fs is shorter than the 600 fs HNNO † lifetime calcu-lated by Bradley et al 6 who used the method of classical trajectories. This suggests that the cluster reaction does not go through the HNNO † intermediate but proceeds via direct attack at the oxygen.…”

“…The large amount of N 2 vibrational excitation reported by Böhmer et al could not be reproduced by the study of Bradley et al, 6 who calculated trajectories and found considerably less N 2 vibrational excitation for reactions that proceed via the HNNO † intermediate. This discrepancy remains unexplained.…”