Crossed molecular beams study of inelastic non-adiabatic processes in gas phase collisions between sodium ions and ZnBr _2 molecules in the 0.10-3.50 keV energy range

摘要

Inelastic electronically non-adiabatic reactions between Na ions and neutral ZnBr _2 molecules, both in their electronic ground state, have been studied using crossed beams techniques and measuring the decaying emission radiation of the excited species produced. The fluorescent emission corresponding to Na(3 ~2P) produced by a charge transfer reaction was observed, as well as that corresponding to the decay of Zn(4s 5s ~3S), generated by dissociation of the neutral target molecule, to Zn(4s 4p ~3P). The phosphorescent decaying emission of Zn(4s 4p ~3P) to the zinc ground state was also observed. For each emission process, the cross section energy dependences have been measured in the 0.10-3.50 keV energy range in the laboratory system. The ground electronic state of the (NaZnBr _2) collision system has been characterized by ab initio chemical structure calculations at the second order M?ller-Plesset perturbation level of theory using pseudo-potentials. By performing restricted open shell Hartree-Fock calculations for C _(2v) geometries, four singlet and four triplet potential energy surfaces of the system have been calculated and used to interpret qualitatively the observed reactions. A simple two-state dynamical model is presented that allows an estimation of the maximum values for measured cross sections at high collision energies to be made.