OBSERVATION OF A LARGE STERIC EFFECT ON THE XEBR-ASTERISK FORMATION IN THE REACTION OF ORIENTED CF3BR WITH XE(P-3)

A large steric effect on XeBr formation was observed in the reaction of oriented CF3Br with Xe(P-3). The reaction cross-section was found t o be largest for the Br-end collisons and smallest for the CS3-end col lisions, even though the electron transfer takes place at relatively l arge internuclear distances in the entrance channel. The large orienta tional dependence may be attributed to the fraction of the collisions that have small impact parameters which can lead to the formation of X eBr. The majority of the collisions, having larger impact parameters, are supposed to lead to electron back-transfer in the exit channel an d are relatively insensitive to the reactant orientation.