Direct measurements of state specific unimolecular dissociation rate constants of highly excited single rotation vibration quantum states of CH3O (X 2E)

Vibration rotation quantum state resolved unimolecular dissociation lifetimes of highly excited CH3O (X̃ 2E) molecules have been measured using the method of stimulated emission pumping (SEP) in connection with transient laser induced fluorescence (TLIF) excitation spectroscopy for preparing selected single target states and for their time resolved detection. The measured decay rate constants for six closely spaced levels with precisely known total excitation energies around E(X̃)≊7450 cm−1 and J=0.5 (or 1.5) were found to vary erratically between 9⋅105 s−1≤k≤3⋅107 s−1. The results are compared to predictions by unimolecular rate theory and discussed with respect to the question of mode specific vs statistical reactivity.