Collisional relaxation of metastable electronic states of Fe+

The overall rate constants for collisional relaxation of metastable excited states of Fe⁺ by He, Ar, Kr, H₂, ²H₂, CO, N₂, NO, CH₄, and CH₃OH have been studied by using charge-exchange ion-molecule reaction chemistry. The rate constants vary according to the nature of the quenching reagent as well as the energy level and electron configuration of the Fe⁺ ions. In general, NO, CH₄, and CH₃OH are the most efficient quenching reagents with rate constants that approach the Langevin collision rate, whereas the reaction rates for the rare gas atoms are slow and vary depending upon the specific electron configuration of the Fe⁺ ion. The mechanism of collisional relaxation is discussed with emphasis on a curve-crossing. mechanism for the rare gas atoms. An electron-transfer mechanism is described for the relaxation of high lying (Fe⁺)*.