Internal Energy Distributions of OH Products in the Reaction of O(3PJ) with HSiCl3

Abstract

The OH(X 2 II, υ=0, 1) internal state distributions from the reaction of electronically ground state oxygen atoms with HSiCl 3 were measured using laser-induced fluorescence. The ground-state 0( 3 Pi) atoms with kinetic energies above the reaction barrier were produced by photolysis of NO 2 at 355 nm. The OH product revealed strong vibrational population inversion, P(υ=1)/Pυ=0) = 4.0 ± 0.6, and rotational distributions in both vibrational states exhibit substantial rotational excitations to the limit of total available energy. However, no preferential populations in either of the two A doublet states were observed from the micropopulations, which supports a mechanism involving a direct abstraction of hydrogen by the atomic oxygen. It was also found that the collision energy between O and HSiCl 3 is effectively coupled into the excitation of the internal degrees of freedom of the OH product ( = 0.62, and = 0.20). The dynamics appear consistent with expectations for the kinematically constrained reaction which supports the reaction type, heavy + light-heavy → heavy-light + heavy (H + LH'→ HL + H'). The dynamics of oxygen atom collision with HSiCl 3 are discussed in comparison to those with SiH 4 .