CH 3 + Cl = CH 3 Cl: RRKM/master equation modeling

Data for the title reaction have been fitted using an RRKM/master equation approach. Energy transfer was modeled using an exponential decay with downward step sizes, ΔE d , as a fitting parameter. The low temperature (200 < T (K) < 300) combination of CH 3 with Cl atoms in He can be accommodated with ΔE d (cm −1 ) = 400. Higher temperature (1600 < T (K) < 2100) decomposition in Ar required ΔE d (T) (cm −1 ) = 694(T/300) 0.46 . Previous analysis of the analogous system CH 4 = CH 3 + H required ΔE d (T) (cm −1 ) = 100(T/300) for He and ΔE d (T) (cm −1 ) = 150(T/300) for Ar. Understanding of the magnitudes and temperature dependence of ΔE d remains the greatest detriment to quantitative calculation, extrapolation, and prediction of unimolecular rate constants. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 245–254, 2009