Radical Association Reactions in Gases at High Pressures

Abstract

AbstractThe pressure dependence of the reactions NO3 + NO2 + M → N2O5 + M, NO2 + NO2 + M → N2O4 + M, H = O2 + M → HO2 + M, CH3 + O2 + M → CH3O2 + M, CH3 + M → C2H6 + M, O2 + O + M → SO2 + M was studied in the fall‐off range approaching the high pressure limit. N2 and other bath gases were used at pressures mostly up to 200 bar. Limiting high and low pressure rate constants k∞ and k0 are reported. The problem of underestimating k0 in extrapolations based only on data from the lowest part of the fall‐off range is demonstrated. Possibilities of the analysis of k∞ are shown by an example for the corresponding specific rate constants k(E, J), which allow comparisons with results from trajectory calculations on ab initio potential surfaces.