Controlling the dissociation dynamics of acetophenone radical cation through excitation of ground and excited state wavepackets

Abstract

Time-resolved measurements of the acetophenone radical cation prepared via adiabatic ionization with strong field 1270 nm excitation reveal coupled wavepacket dynamics that depend on the intensity of the 790 nm probe pulse. At probe intensities below W cm−2, out of phase oscillations between the parent molecular ion and the benzoyl fragment ion are shown to arise from a one-photon excitation from the ground D0 ionic surface to the D1 and/or D2 excited surfaces by the probe pulse. At higher probe intensities, a second set of wavepacket dynamics are observed that couple the benzoyl ion to the phenyl, butadienyl, and acylium fragment ions. Equation of motion coupled cluster calculations of the ten lowest lying ionic surfaces and the dipole couplings between the ground ionic surface D0 and the nine excited states enable elucidation of the dissociation pathways and deduction of potential dissociation mechanisms. The results can lead to improved control schemes for selective dissociation of the acetophenone radical cation.