Anisotropic photodissociation of CH3Cl

Photodissociation of the methyl chloride ion has been investigated using mass-analyzed ion kinetic spectrometry (MIKES). The MIKE spectrum for the chlorine atom loss from the methyl chloride ion has been measured as a function of the laser polarization angle at 357, 488.0, and 514.5 nm. The anisotropy parameters and kinetic energy release distributions have been determined. At all the wavelengths used, an anisotropic dissociation (β=1.2) in the repulsive excited electronic state has been observed. Results from quantum chemical calculations carried out at the various levels suggest that the methyl chloride ion is excited to the first excited electronic state A, and dissociates repulsively in this state.