Direct measurements of methoxy removal rate constants for collisions with CH4, Ar, N2, Xe, and CF4 in the temperature range 673--973K

Removal rate constants for CH3O by CH4, Ar, N2, Xe, and CF4 were measured over a 400K temperature range using a laser photolysis/laser-induced fluorescence technique. Rapid methoxy removal rates are observed for the non-reactive collision partners (Ar, N2, Xe, and CF4) at elevated temperatures showing that the dissociation and isomerization channels for CH3O are indeed important. The total removal rate constant (reaction /plus/ dissociation and/or isomerization) for CH4 exhibits a linear dependence on temperature and has a removal rate constant, k/sub r/ /equals/ (1.2 +- 0.6) /times/ 10/sup /minus/8/exp[(/minus/101070 +- 350)/T]cm3molecule/sup /minus/1/s/sup /minus/1/. Assuming that the removal rate constant due to dissociation and/or isomerization are similar for CH4 and CF4, the reaction rate constant for CH3O /plus/ CH4 is equal to (1.7 +- 1.0) /times/ 10/sup /minus/10/exp[(/minus/7480 +- 1100)/T]cm3molecule/sup /minus/1/s/sup /minus/1/. 7 refs., 4 figs