Spectroscopy and dynamics of A [2B1] allyl radical

The A [B-2(1)] <- X[(2)A(2)] 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.