Spectroscopy and dynamics of A [2B1] allyl radical

Abstract

The A [²B₁] ← X [²A₂] band system between 380 and 420 nm was observed in a supersonic jet expansion. The allyl radical was found to dissociate following electronic excitation, releasing a hydrogen atom. Monitoring the appearance of the hydrogen atom photoproduct as a function of the excitation laser wavelength, similar spectral features are observed as in earlier absorption experiments. Time- and frequency-resolved photoionization of the hydrogen atom product provides information on the unimolecular dissociation dynamics. The measured dissociation rates and kinetic energy releases of both allyl radical, C₃H₅, and partially deuterated allyl radical, C₃DH₄, suggest direct loss of the central hydrogen atom, leading to allene as the major product.