Dissociative Recombination of K₂⁺ and Rb₂⁺ in Diode-Pumped Alkali Lasers: Potential Energy Curves and Atomic Products

Abstract

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+, 3Σ+, 1Δ, 3Δ, 1Π, 3Π, 1Φ, and 3Φ valence states of K2 and Rb2 that 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 23Δu and 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 Rb2 are 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.