The Jahn–Teller effect in the ground electronic state of the tetrafluoromethane cation before dissociation: a promoter of the anisotropic fragmentation

ABSTRACTThe role of multimode T1⊗(e+t2) Jahn–Teller coupling effect on the anisotropic fragmentation of CF4+ in its X~2T1 electronic state is investigated theoretically via an ab initio  quantum dynamics study. The potential energy surfaces up to two-dimensions of nuclear coordinates are established from extensive electronic structure calculations. A higher order (seventh-order) diabatic vibronic coupling model Hamiltonian is necessary to mimic the ab initio  potentials and thereby constructed. The theoretical results are in good agreement with experimental observations. A detail analysis of the relevant static aspects and the vibrational progressions under the structureless and broad X~2T1  vibronic band of CF4+ are made. Present study suggests that the Jahn–Teller effect is operative before the dissociation of CF4 upon photoionisation and responsible for the experimentally measured anisotropic fragmentation in the X~2T1  electronic state of the title cation.