aDepartment of Quantum Chemistry, Uppsala University, Box 518, SE-751 20 Uppsala, Sweden
bDepartment of Photochemistry and Molecular Science, Box 523, SE-751 20 Uppsala, Sweden
Abstract:
Dissociation of chlorobenzene via the lowest singlet excited state has been investigated by means of pump–probe femtosecond spectroscopy and spin–orbit corrected ab initio quantum chemistry. We have found that the so far accepted model with a 1ππ* → 3π/nσ* reaction mechanism has to be amended. We suggest that the mechanism goes via a transition from 1ππ* to a πσ* state that is to 90% a singlet. Further, three nuclear degrees of freedom required to describe the dissociation have been defined.