Coherent control of interference between one- and two-photon dissociation of allyl iodide

We have investigated the interference effects between two coherent excitation pathways in photodissociation of allyl iodide by using nanosecond light and its second-harmonic light. We have performed one-dimensional photofragment translational spectroscopy on allyl iodide in the presence of simultaneous one- and two-photon excitation. The yield of the spin–orbit excited iodine atoms dissociated from allyl iodide molecules shows an oscillating behavior that is dependent on the relative phase between the fundamental and the second-harmonic light. This phase-dependent behavior can be explained by the interference between a one-photon transition induced by the second-harmonic light and a two-photon transition resulting from lack of symmetry of allyl iodide with respect to inversion.