Collisional Deactivation of Vibrationally Excited sec-Butyl-d1 Radicals Produced by Chemical Activation

Vibrationally excited sec-butyl-d1 radicals have been produced by addition of D atoms to cis-butene-2. The radicals, which have a narrow range of internal energy E, undergo either collisional stabilization (S) or decomposition (D) with specific rate kE. The ratio D/S has been studied as a function of pressure down to 0.005 mm at 25°. Using calculated values of kE, information is obtained about vibrational transitions upon collision of excited radicals with butene molecules, under different assumptions regarding the form of the transition probability function. It is shown that in these cases the average energy transferred is at least 8.5 kcal/mole, and quite probably much more, which supports the conventional Lindemann collisional activation-deactivation assumption of strong collisions in this case.