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

Dissociative recombination (DR) of K and Rb 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 K and Rb molecular ions and of the diabatic Σ, Σ, Δ, Δ, Π, Π, Φ, and Φ valence states of K and Rb 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 6Σ, 5Σ, and 2Δ and for Rb only 6Σ. The excited states of K atoms produced by DR are 4P and 5P. Most of the Rb atoms produced by DR are in the 6P excited state, while a small fraction of the atoms produced by the less likely routes along two states of Rb are in the 5P 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.