Photodissociation dynamics of tert-butyl hydroperoxide at 213 nm via degenerate four-wave mixing spectroscopy

The photodissociation dynamics of t-BuOOH at 213 nm has been studied using degenerate four-wave mixing spectroscopy. The internal energy distribution, Λ-doublet ratio and spin-orbit state ratio of OH (X²∏, υ″ = 0) fragments were extracted. The OH radicals were found to be vibrationally cold with an average rotational energy of 1726 cm^-1, indicating that 5.0% of the available energy was transferred into the OH rotational degree of freedom. A Gaussian distribution of product rotational energy was observed. The population was found to be distributed statistically between the two spin-orbit states. A preferential population of the π⁺ A-doublet was observed irrespective of N without inversion. The observed Λ-doublet nonequilibrium implies that splitting of energy levels may occur because of the breaking of symmetry due to substitution. We suggest that the hydroxyl part should be the dominant chromophore for the absorption of t-BuOOH at 213 nm.