Dissociative Recombination of K 2⁺and Rb 2⁺in Diode-Pumped Alkali Lasers: Potential Energy Curves and Atomic Products

Dissociative recombination (DR) of K2⁺and Rb2⁺ions is one of the most important processes in K and Rb diode-pumped alkali lasers (DPALs) strongly affecting their power. We report on the calculations of potential energy curves of the K2⁺and Rb2⁺molecular ions and of the diabatic ¹ς^{+ 3}ς^{+ 1}Δ, ³Δ, ¹Π, ³Π, ¹φ, and ³φ valence states of K₂and Rb₂that provide the routes for DR of the ions. These curves are required for subsequent calculations of DR rate constants. It was found that the most likely DR routes for K are along the dissociative states 6¹ςg⁺, 5³ςu⁺, and 2³Δ_uand for Rb only 6¹ςg⁺. The excited states of K atoms produced by DR are 4²P and 5²P. Most of the Rb atoms produced by DR are in the 6²P excited state, while a small fraction of the atoms produced by the less likely routes along two states of Rb₂are in the 5²P state. This conclusion contradicts the kinetic scheme for K and Rb DPAL proposed elsewhere, and thus the kinetic schemes of these DPALs should be modified according to the present results.