title: Dissociation limit and dissociation dynamic of CF4(+): application of threshold photoelectron-photoion coincidence velocity imaging.
abstract: Dissociation of internal energy selected CF4(+) ions in an excitation energy range of 15.40-19.60 eV has been investigated using threshold photoelectron-photoion coincidence (TPEPICO) velocity imaging. Only CF3(+) fragment ions are observed in coincident mass spectra, indicating all the X(2)T1, A(2)T2, and B(2)E ionic states of CF4(+) are fully dissociative. Both kinetic energy released distribution (KERD) and angular distribution in dissociation of CF4(+) ions have been derived from three-dimensional TPEPICO time-sliced images. A parallel distribution of CF3(+) fragments along the polarization vector of photon is observed for dissociation of CF4(+) ions in all the low-lying electronic states. With the aid of F-loss potential energy curves, dissociation mechanisms of CF4(+) ions in these electronic states have been proposed. CF4(+) ions in both X(2)T1 and A(2)T2 states directly dissociate to CF3(+) and F fragments along the repulsive C-F coordinate, while a two-step dissociation mechanism is suggested for B(2)E state: CF4(+)(B(2)E) ion first converts to the lower A(2)T2 state via internal conversion, then dissociates to CF3(+) and F fragments along the steep A(2)T2 potential energy surface. In addition, an adiabatic appearance potential of AP0(CF3(+)∕CF4) has also been established to be 14.71 ± 0.02 eV, which is very consistent with the recent calculated values.
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Tang
authors.forename: Xiaoguo
authors.initials: X
authors.lastname: Zhou
authors.forename: Manman
authors.initials: M
authors.lastname: Wu
authors.forename: Zhi
authors.initials: Z
authors.lastname: Gao
authors.forename: Shilin
authors.initials: S
authors.lastname: Liu
authors.forename: Fuyi
authors.initials: F
authors.lastname: Liu
authors.forename: Xiaobin
authors.initials: X
authors.lastname: Shan
authors.forename: Liusi
authors.initials: L
authors.lastname: Sheng