Abstract
Concerted elimination pathway leading to Br2+ and C2H4+ results from the two-body Coulomb explosion of from 1,2-dibromoethane molecule in 800nm femtosecond laser field via a TS structure. In the TS structure, the dihedral angle Φ(BrCCBr) decreased to 72°, both C–Br bonds are elongated to 1.94Å, and thus the distance between two Br atoms is shortened to 3.50Å. After surpassing the energy barrier (TS), the doubly charged precursor dissociates into Br2+ and C2H4+ through CE process. The Br2+ elimination is a synchronous concerted reaction. [Display omitted]
•Br2+ and C2H4+ ejections from 1,2-dibromoethane is observed.•Br2+ ejections is a synchronous concerted elimination.•Br2+ and C2H4+ results from the two-body CE of the doubly charged parent ion 1,2-DBE2+.•Br2+ and C2H4+ are dissociated after surpassing the energy barrier of a TS structure.
Concerted elimination pathway leading to Br2+ and C2H4+ from 1,2-dibromoethane molecule has been investigated in 800nm femtosecond laser field by dc-slice imaging technology. The kinetic energy release and angular distributions of Br2+ and C2H4+ demonstrate that Br2+ results from the two-body Coulomb explosion of the doubly charged parent ion. Ab initio calculations show that the doubly charged precursor overcomes a small energy barrier (0.18eV) and then dissociates into Br2+ and C2H4+ through a synchronous concerted elimination mechanism. Moreover, the relative yield of the Br2+ channel is obtained, and it remains about 3.4% when the laser intensity exceeds 1.0×1014W/cm2.
