Concerted elimination of Br+2 resulting from the Coulomb explosion of 1,2-dibromoethane in an intense femtosecond laser field

Concerted elimination pathway leading to Br-2(+) and C2H4+ from 1,2-dibromoethane molecule has been investigated in 800 nm femtosecond laser field by dc-slice imaging technology. The kinetic energy release and angular distributions of Br-2(+) and C2H4+ demonstrate that Br-2(+) 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 (0.18 eV) and then dissociates into Br-2(+) and C2H4+ through a synchronous concerted elimination mechanism. Moreover, the relative yield of the Br-2(+) channel is obtained, and it remains about 3.4% when the laser intensity exceeds 1.0 x 10(14) W/cm(2). (C) 2014 Elsevier B.V. All rights reserved.