Reactive scattering of a supersonic oxygen atom beam : O + CF3I

Abstract

Reactive scattering of O atoms with CF3I molecules has been studied at an initial translational energy E = 32 kJ mol-1 using a supersonic beam of O atoms seeded in He and at E = 14 kJ mol-1 using O atoms seeded in Ne. Velocity distributions of OI product were measured by cross-correlation time-of-flight analysis. Full contour maps of the differential reaction cross-section have been obtained which favour the backward hemisphere for O atoms seeded in Ne but become essentially isotropic for O atoms seeded in He. The average product translational energy is approximately equal to the initial translational energy for both O atoms seeded in He and Ne. However, the product translational energy distributions are skewed with respect to the initial translational energy distributions with a peak at lower energy and a tail extending to higher energy. These results indicate that reaction occurs only in collisions at small impact parameters b 2 Å with repulsion between reaction products arising from hard sphere interactions at small internuclear distances. However, the skewed form of the product translational energy distribution indicates that significant energy exchange also occurs with the internal modes of the polyatomic CF3 radical.