Monte Carlo calculations of reaction rates and energy distributions among reaction products. Reactions of HF and DF with H and D-atoms

Abstract

Rate coefficients are calculated for the reactions of H and D-atoms with vibrationally excited HF and DF molecules. Three-dimensional classical trajectories of the collision dynamics of these reactions have been calculated by means of the London-Eyring-Polanyi-Sato (LEPS) potential energy surface. The Monte Carlo procedure is used to start each collision trajectory. Results of this study indicate that (a) chemical exchange provides an efficient mechanism for relaxing vibrationally excited HF and DF molecules by H and D-atoms; (b) multiple-quantum transitions are important in the deactivation processes; and (c) both vibration-translation and vibration-rotation energy transfers contribute to vibrational relaxation of vibrationally excited HF and DF molecules by H and D-atoms. The vibrational relaxation of HF (v = 1) by H-atoms is faster than the vibrational relaxation of DF (v = 1) by H-atoms. A similar effect is indicated for D-atoms; i.e. the vibrational relaxation of DF (v = 1) by D-atoms is faster than the vibrational relaxation of HF (v = 1) by D-atoms. Room temperature vibration to translation-rotation (V → T, R) relaxation rates in units of (μsec Torr)^-1 are as follows: 13·8 × 10^-2 for HF (v = 1) by H, 3·1 × 10^-2 for DF (v = 1) by D, 5·5 × 10^-3 for HF (v = 1) by D, and 1·9 × 10^-2 for DF (v = 1) by H. Rates of deactivation of vibrationally excited HF and DF molecules by H and D-atoms are very fast. Rate coefficients are provided for many reactions that have not been measured experimentally.

This work reflects research supported by the Air Force Weapons Laboratory under U.S. Air Force Space and Missile Systems Organization (SAMSO), Contract F04701-73-C-0074.

This work reflects research supported by the Air Force Weapons Laboratory under U.S. Air Force Space and Missile Systems Organization (SAMSO), Contract F04701-73-C-0074.

Notes

This work reflects research supported by the Air Force Weapons Laboratory under U.S. Air Force Space and Missile Systems Organization (SAMSO), Contract F04701-73-C-0074.