UV photodissociation of methyl bromide and methyl bromide cation studied by velocity map imaging

We employ the velocity map imaging technique to measure kinetic energy and angular distributions of state selected CH(3) (v(2)=0,1,2,3) and Br ((2)P(3/2), (2)P(1/2)) photofragments produced by methyl bromide photolysis at 215.9 nm. These results show unambiguously that the Br and Br( *) forming channels result in different vibrational excitations of the umbrella mode of the methyl fragment. Low energy structured features appear on the images, which arise from CH(3)Br(+) photodissociation near 330 nm. The excess energy of the probe laser photon is channeled into CH(3) (+) vibrational excitation, most probably in the nu(4) degenerate bend.