Photodissociation of Methyl Iodide and Methyl Iodide Clusters at 193 nm

Abstract

This study introduces the state resolved dynamics of CH3I when clustered in a supersonic expansion using He and Xe as seeding gases. Following excitation at 193 nm (6.4 eV), state specific alterations in photodissociation dynamics are observed. Four vibrational levels (ν2 = 0, 1, 2, 3) of the CH3 umbrella vibrational mode were probed, as were I(2P3/2) and I(2P1/2) atomic photofragments. For nascent CH3 fragments the measured kinetic energy releases and angular distributions show enormous sensitivity to the clustering. Manifestation of the clustering dynamics include: (a) shifting to higher energies (by up to 0.5 eV) and significant broadening of the kinetic energy distribution; (b) vibrational dependence of this increase in product kinetic energy; (c) angular distribution changes from a characteristic perpendicular character observed in free-standing CH3I into a parallel transition for the clustered moiety. Drastic effects of clustering are also observed when probing iodine-atom photofragments, namely the...