Dynamics of vibrationally mediated photodissociation of CH3CFCl2

The ∼235 nm photodissociation of CH3CFCl2 pre-excited to three, four, and five quanta of C–H methyl stretches was studied to investigate the effect of internal parent excitation on the dynamics of two- and three-body photofragmentation. The ∼235 nm photons also tagged spin-orbit ground Cl 2P3/2 [Cl] and excited Cl 2P1/2 [Cl*] state photofragments, via (2+1) resonantly enhanced multiphoton ionization in a time-of-flight mass spectrometer. Monitoring the shapes of 35Cl and 35Cl* time-of-arrival profiles revealed their energies and angular distributions and showed broad and unstructured fragment kinetic energy distributions. Although a significant amount (∼50%) of the available energy is transferred into internal energy of the CH3CFCl fragment, the spatial Cl distribution is characterized by a nonvanishing anisotropy parameter, β, which indicates at a fast dissociation of the parent molecule along the C–Cl dissociation coordinate. Moreover, β for Cl changes from a slightly positive value to a negative value,...