Infrared Emission from the Reaction of CHF (X̃A‘) with NO

Abstract

Infrared emission has been observed from the reaction of the CHF (X 1 A′) radical with NO (X 2 Π). The carbene radical was formed by infrared multiphoton dissociation (IRMPD) of either the CH 2 FCl or the CH 2 F 2 precursor, and emission in the 1850-4500-cm -1 region was observed by a time-resolved Fourier transform infrared (FTIR) technique. Emissions have been identified from the HF product of the reaction and from species produced by the subsequent reaction of the NCO radical product with NO. The HF was found to possess more than a statistical share of the available energy in vibration. Addition of D 2 to the system results in DF formed from the reaction of F atoms, and comparison of the HF/DF emission intensities has allowed the relative branching ratio of the CHF + NO reaction forming HF and F products to be 0.6 ( 0.04:0.4 ( 0.03.

Theoretical study on the mechanism of the 1CHCl + NO reaction

“…The theoretical product distributions are in marked difference from the experimental one, that is, HF ϩ NCO (60%) and F ϩ HNCO (40%). 11 By comparing the theoretical results of the three analogous reactions CHX ϩ NO (XAF, Cl, H), we find that the process HXCNO 3 c-C(HX)NO 3 HNC(X)O or XNC(H)O plays a very important role, that is, Path 2-3 for the 3 CH 2 ϩ NO reaction, Path 2-3 for the 1 CHF ϩ NO reaction, Path P 1 -P 7 , P 13 , and P 14 for the 1 CHCl ϩ NO reaction. Concerning the major product (Path 1 H ϩ HCNO and Path P 9 (I) Cl ϩ HCNO that are both formed via direct COX bond cleavage of isomer HXCNO), the 1 CHCl ϩ NO reaction is more similar to 3 CH 2 ϩ NO than to 1 CHF ϩ NO.…”

“…10 Thus, the title reaction may be very effective in NO-reduction in atmospheric and combustion chemistry and may thus be considered as an important process, referred to as "reburning." NCO (60%) and F ϩ HNCO (40%), 11 suggesting further experimental studies are necessary. Surely, the product distributions of the above two reactions have significant discrepancies.…”

“…1 The simplest halogenated carbene, CHF, has received considerable attention for its electronic structure, formation enthalpy, and reaction kinetics. [2][3][4][5][6][7][8][9][10][11][12] For the CHCl carbene, there have been some experimental and theoretical measurements on its electronic structure and formation enthalpy. 2 However, to our best knowledge, only one experimental study has been reported on the rate constants of the CHCl reactions with NO and O 2 .…”

“…Bond distances are in angstroms and angles are in degrees. NCO (60%) and F ϩ HNCO (40%), 11 suggesting further experimental studies are necessary. Surely, the product distributions of the above two reactions have significant discrepancies.…”

“…Both P 13 (Ϫ10.3 kcal/mol) and P14 (Ϫ9.1 kcal/mol) lie high in energy. Their formation pathways are as follows: Path P13 (I) R 3 a1 (a2) 3 13 ClNC ؉ OH Path P13 (II) R 3 a1 (a2) 3 13 H ؉ ClNCO Path P14 (II) R 3 a1 (a2) 3 13 H ؉ ClNCO Other ProductsNow we consider the products P 4 CO ϩ NClH (Ϫ71.1 kcal/mol), P 5 OH ϩ ClCN (Ϫ54.6 kcal/mol), P8 HCl ϩ CNO (Ϫ27.5 kcal/mol), P10 ClO ϩ HNC (Ϫ17.4 kcal/mol), P11 3 NH ϩ ClCO (Ϫ19.5 kcal/mol), P12 HCl ϩ c-CNO (Ϫ13.9 kcal/mol), P15 CN ϩ HOCl (Ϫ4.8 kcal/mol), P16 H ϩ ClOCN (0.8 kcal/mol), and P 17 H ϩ ClCNO (7.4 kcal/mol). Except for P…”