title: Photodissociation dynamics of CH(2)Br(2) near 234 and 267 nm.
abstract: The photodissociation dynamics of CH(2)Br(2) was investigated near 234 and 267 nm. A two-dimensional photofragment ion velocity imaging technique coupled with a [2+1] resonance-enhanced multiphoton (REMPI) ionization scheme was utilized to obtain the angular and translational energy distributions of the nascent Br ((2)P(3/2)) and Br* ((2)P(1/2)) atoms. The obtained translational energy distributions of Br and Br* are found consist of two components which should be come from the radical channel and secondary dissociation process, respectively. It is suggested that the symmetry reduction from C(2v) to C(s) during photodissociation invokes a non-adiabatic coupling between the 2B(1) and A(1) states. Consequently, the higher internal energy distribution of Br channel than Br* formation channel and the broader translational energy distribution of the former are presumed correlate with a variety of vibrational excitation disposal at the crossing point resulting from the larger non-adiabatic crossing from 2B(1) to A(1) state than the reverse crossing. Moreover, the measured anisotropy parameter beta indicate that fragments recoil along the Br-Br direction mostly in the photodissociation.
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China.
authors.forename: Lei
authors.initials: L
authors.lastname: Ji
authors.forename: Ying
authors.initials: Y
authors.lastname: Tang
authors.forename: Rongshu
authors.initials: R
authors.lastname: Zhu
authors.forename: Zhengrong
authors.initials: Z
authors.lastname: Wei
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
mesh_terms: D001966:Bromine / Q000737:chemistry*; D002151:Calorimetry; D006842:Hydrocarbons, Brominated / Q000737:chemistry*; D007700:Kinetics; D013058:Mass Spectrometry; D010782:Photolysis; D017785:Photons; D013056:Spectrophotometry, Ultraviolet
chemical_list: D006842:Hydrocarbons, Brominated; C005218:methyl bromide; D001966:Bromine; C027947:methylene bromide