The high‐pressure range of the reaction of CH(2Π) with N2

Competing Channels in the Propene + OH Reaction: Experiment and Validated Modeling over a Broad Temperature and Pressure Range

Although the propene + OH reaction has been in the center of interest of numerous experimental and theoretical studies, rate coefficients have never been determined experimentally between ∼600 and ∼750 K, where the reaction is governed by the complex interaction of addition, back-dissociation and abstraction. In this work OH time-profiles are measured in two independent laboratories over a wide temperature region (200–950 K) and are analyzed incorporating recent theoretical results. The datasets are consistent both with each other and with the calculated rate coefficients. We present a simplified set of reactions validated over a broad temperature and pressure range, that can be used in smaller combustion models for propene + OH. In addition, the experimentally observed kinetic isotope effect for the abstraction is rationalized using ab initio calculations and variational transition-state theory. We recommend the following approximate description of the OH + C3H6 reaction

C3H6 + OH ⇆ C3H6OH (R1a,R-1a)

C3H6 + OH → C3H5 + H2O (R1b)

k 1a (200 K ≤ T ≤ 950 K; 1 bar ≤ P) = 1.45 × 10-11 (T/K)-0.18 e 460 K/T cm3 molecule-1 s-1

k -1a (200 K ≤ T ≤ 950 K; 1 bar ≤ P) = 5.74 × 1012 e -12690 K/T s-1

k 1b (200 K ≤ T ≤ 950 K) = 1.63 × 10-18 (T/K)2.36 e -725 K/T cm3 molecule-1 s-1

D atom loss in the photodissociation of the DNCN radical: Implications for prompt NO formation

The photodissociation of DNCN following excitation of the C 2A"<--X 2A" electronic transition was studied using fast beam photofragment translational spectroscopy. Analysis of the time-of-flight distributions reveals a photodissociation channel leading to D+NCN competitive with the previously observed CD+N2 product channel. The translational energy distributions describing the D+NCN channel are peaked at low energy, consistent with internal conversion to the ground state followed by statistical decay and the absence of an exit barrier. The results suggest a relatively facile pathway for the reaction CH+N2-->H+NCN that proceeds through the HNCN intermediate and support a recently proposed mechanism for prompt NO production in flames.

Photodissociation dynamics of the HCNN radical

The photodissociation dynamics of the diazomethyl (HCNN) radical have been studied using fast radical beam photofragment translational spectroscopy. A photofragment yield spectrum was obtained for the range of 25,510-40,820 cm(-1), and photodissociation was shown to occur for energies above 25,600 cm(-1). The only product channel observed was the formation of CH and N2. Fragment translational energy and angular distributions were obtained at several energies in the range covered by the photofragment yield spectrum. The fragment translational energy distributions showed at least two distinct features at energies up to 4.59 eV, and were not well fit by phase space theory at any of the excitation energies studied. A revised C-N bond dissociation energy and heat of formation for HCNN, D0(HC-NN)=1.139+/-0.019 eV and DeltafH0(HCNN)=5.010+/-0.023 eV, were determined.

The CH + N2 Association Reaction at Low Temperatures: Ab Initio MO/VRRKM-Theory Analysis of Temperature and Pressure Effects

The microcanonical variational RRKM formalism combined with high level

A Saturated LIF Study on the High Pressure Limiting Rate Constant of the Reaction CN + NO + M → NCNO + M between 200 and 600 K

The reaction CN + NO + M ↔ NCNO + M was studied in the bath gas helium at temperatures between 200 and 600 K and in the pressure range between 1 and 100 bar. CN radicals were generated by laser flash photolysis of BrCN at 193 nm in the presence of NO and high helium pressures. The concentration of CN radicals was detected by recording their non-resonant fluorescence yield at 420 nm after delayed excitation in the (0, 1)-band of the X