Theoretical and Experimental Investigation of the Dynamics of the Production of CO for CH3 + O and CD3 + O Reactions

Published

September 1, 2001

Author(s)

T P. Marcy, R R. Diaz, Dwayne E. Heard, S R. Leone, L B. Harding, S J. Klippenstein

Abstract

Combined experimental and theoretical investigations of the title reactions are presented. Time-resolved Fourier transform infrared (FTIR) emission studies of CO (upsilon = 1) produced from the CH₃ + O and CD₃ + O reactions show that there is approximately a one-thirdc reduction in the branching to the CO channel upon deuteration of the methyl radical. Direct dynamics, classical trajectory calculations using a B3LYP potential surface, confirm the existence of the CO producing channel. The calculations show that the CO comes from the decomposition of HCO produced by the elimination of H₂ from highly vibrationally excited methoxy radicals. Scans of the potential surface reveal no saddle point for the direct elimination of H₂ from methoxy. The minimum-energy path for this elimination is a stepwise process involving first a CH bond cleavage, forming H + H₂CO, followed by an abstraction, forming H₂ + HCO, However, at the high internal energies produced in the initial O + CH₃ addition, trajectories for the direct elimination of H₂ from methoxy are observed. The predicted branching ratio between the CO and H₂CO channels is in good agreement with previous room-temperature measurements, and there is predicted to be little temperature dependence to it. The observed reduction in the branching to the CO channel upon deuteration is also well reproduced in the calculations.

Citation

Journal of Physical Chemistry A

Volume

105

Issue

No. 36

Pub Type

Journals

Keywords

Fourier transform infrared (FTIR)

Citation

Marcy, T. , Diaz, R. , Heard, D. , Leone, S. , Harding, L. and Klippenstein, S. (2001), Theoretical and Experimental Investigation of the Dynamics of the Production of CO for CH₃ + O and CD₃ + O Reactions, Journal of Physical Chemistry A (Accessed July 27, 2024)