Unimolecular decomposition of t-butylhydroperoxide by direct excitation of the 6–0 O—H stretching overtone

Abstract

The kinetics of the unimolecular decomposition of t-butylhydroperoxide [(CH₃)₃COOH] have been investigated when energy is deposited into 6 quanta of the O—H stretch, causing fission of the O—O bond. The 6–0 O—H overtone is pumped at 532 nm and the appearance of one of the ultimate products, t-butyl alcohol, is detected using optoacoustic spectroscopy to follow the reaction in situ. The results of the present work are compared with previous dissociation studies using direct overtone pumping at both 532 and 619 nm. The appearance rate of t-butyl alcohol as a function of pressure is not consistent with an R.R.K.M. treatment based on simple Stern–Volmer kinetics, but can be adequately fit by invoking collisional transfer to an electronic state, which decomposes more rapidly than the ground state, and/or invoking non-statistical behaviour.