Photodissociation dynamics of the propargyl bromide molecular ion

Photodissociation of the propargyl bromide molecular ion has been investigated using mass-analyzed ion kinetic energy spectrometry (MIKES). The MIKE spectra for the bromine loss has been measured as a function of the laser polarization angle at 357, 488.0, 514.5, and 607.5 nm. A convenient analytic method to treat the MIKE profile has been developed and the anisotropy parameters and kinetic energy release distributions (KERDs) have been determined by analyzing the experimental data. At all the wavelengths used, an anisotropic dissociation in the repulsive excited electronic state(s) has been observed. In addition, the statistical dissociation in the ground electronic state has been observed at 357 and 607.5 nm. Results from quantum chemical calculations carried out at the TDDFT/UB3LYP level using the 6-311++G** basis set will be discussed in relation to the nature of the repulsive excited electronic state involved.