Reaction of CH radical with O2 by time-resolved FTIR spectroscopy

Ren, Li; Kong, Fanzuo

doi:10.1007/bf03183942

Cited by 2 publications

(1 citation statement)

References 20 publications

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“…Bromoform is a common precursor for the CH radical − by UV photolysis. In many cases, it can be assumed that the dissociation of bromoform is sequential; that is, after absorption of a single photon, bromoform dissociates into CHBr 2 + Br, and then, CHBr 2 absorbs another single photon, etc.…”

Section: Introductionmentioning

confidence: 99%

State-Resolved Dynamics of the CH(A²Δ) Channels from Single and Multiple Photon Dissociation of Bromoform in the 10−20 eV Energy Range

et al. 2005

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Single photon dissociation of bromoform using synchrotron radiation has been investigated by Fourier transform visible fluorescence spectroscopy (FTVIS). The photodissociation of bromoform in the 12-18 eV energy range results in several products, among which are the CH(A2Delta) and CH(B2Sigma) radicals. Vibrational and rotational state distributions of the CH(A2Delta) are determined from their fluorescence spectra. From the threshold photon energy above which emission from the CH(A2Delta) radicals is observed, the most likely process leading to CH(A) formation is CHBr3 --> CH + 3Br rather than CHBr3 --> CH + Br + Br2. The rotational Boltzmann temperatures in the CH(A --> X) emission spectra for v' = 0 and v' = 1 range between 1570 and 3650 K, depending on the excitation photon energy. From the high rotational excitation, the results suggest that the mechanism for the loss of three bromine atoms is most likely sequential. A small negative emission anisotropy of the CH(A) radicals [(Ipar - Iper)/(Ipar + 2Iper) = -0.024 +/- 0.005] is constant across the action spectrum; a small net absorption dipole of CHBr3 in the vacuum ultraviolet is parallel to the 3-fold symmetry axis of the CHBr3 molecule. The state distributions of the CH(A2Delta) radicals from multiphoton dissociation of bromoform using the 266 nm output (three photons) of a femtosecond laser (Boltzmann temperatures: T(v'=0)(rot)= 4250 +/- 300 K; T(v'=1)(rot)= 3100 +/- 550 K) are compared to those from the single photon dissociation results (Boltzmann temperatures: T(v'=0)(rot)= 3650 +/- 150 K; T(v'=1)(rot)= 2400 +/- 200 K) at the same total excitation energy under collision free conditions. The analysis of the CH(A) rotational populations shows hotter rotational populations for the femtosecond experiment, also suggesting sequential dissociation of the bromoform in the femtosecond experiment. The duration of the femtosecond laser pulse is approximately 180 fs, setting a limit on the time scales for the multiple dissociations.

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Section: Introductionmentioning

confidence: 99%

State-Resolved Dynamics of the CH(A²Δ) Channels from Single and Multiple Photon Dissociation of Bromoform in the 10−20 eV Energy Range

et al. 2005

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A single‐ and multireference study on CH (X²Π) reaction with O₂ ()

Keshavarz

Mousavipour

2018

Int J of Chemical Kinetics

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This study focuses on the dynamics of the reaction of CH (X 2 Π) radicals with O 2 (X 3 Σ − ) in the presence of N 2 , as the bath gas molecule. A general description of the reaction mechanism was investigated by employing molecular dynamics simulations with an implanted reactive force field under a realistic system that could account for both reactive and nonreactive collisions. This tool helped to provide an initial guess for the reaction mechanism to unravel some information about the potential reaction paths and secondary products. The initial guess was used to explore the detailed reaction mechanism quantum mechanically over the lowest doublet and quadruplet surfaces at the single-reference level of CCSD(T)/aug-cc-pVTZ and the multireference level of CASPT2/aug-cc-pVTZ. The theoretical bimolecular reaction rate constants were computed by solving a master equation over the lowest doublet single-and multireference potential energy surfaces. The calculated rate constant for loss of the reactants and formation of the HCO and CO products declared noticeable agreement with the available experimental rate constants. HCO, CO, and CO 2 are identified as the main products along with the following single-reference (multireference)-based product branching ratios at 450 K: [triangular 1 CO 2 + 2 H and linear 1 CO 2 + 2 H]: 69.1% (79.3%); 1 CO + 2 OH: 18.2% (15.0%); 2 HCO + 3 O: 12.7% (5.7%). Both single-and multireference calculations demonstrated reliable chemical kinetics results, in the context of the available experimental rate constants and resulted in fair agreement with the experimentally reported branching ratios. K E Y W O R D S

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Reaction of CH radical with O2 by time-resolved FTIR spectroscopy

Cited by 2 publications

References 20 publications

State-Resolved Dynamics of the CH(A²Δ) Channels from Single and Multiple Photon Dissociation of Bromoform in the 10−20 eV Energy Range

State-Resolved Dynamics of the CH(A²Δ) Channels from Single and Multiple Photon Dissociation of Bromoform in the 10−20 eV Energy Range

A single‐ and multireference study on CH (X²Π) reaction with O₂ ()

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Reaction of CH radical with O2 by time-resolved FTIR spectroscopy

Cited by 2 publications

References 20 publications

State-Resolved Dynamics of the CH(A2Δ) Channels from Single and Multiple Photon Dissociation of Bromoform in the 10−20 eV Energy Range

State-Resolved Dynamics of the CH(A2Δ) Channels from Single and Multiple Photon Dissociation of Bromoform in the 10−20 eV Energy Range

A single‐ and multireference study on CH (X2Π) reaction with O2 ()

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State-Resolved Dynamics of the CH(A²Δ) Channels from Single and Multiple Photon Dissociation of Bromoform in the 10−20 eV Energy Range

State-Resolved Dynamics of the CH(A²Δ) Channels from Single and Multiple Photon Dissociation of Bromoform in the 10−20 eV Energy Range

A single‐ and multireference study on CH (X²Π) reaction with O₂ ()