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

Dissociative recombination (DR) of K 2 + and Rb 2 + 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 2 + and Rb 2 + molecular ions and of the diabatic 1 Σ + , 3 Σ + , 1 Δ, 3 Δ, 1 Π, 3 Π, 1 Φ, and 3 Φ valence states of K 2 and Rb 2 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 6 1 Σ g + , 5 3 Σ u + , and 2 3 Δ u and for Rb only 6 1 Σ g + . The excited states of K atoms produced by DR are 4 2 P and 5 2 P. Most of the Rb atoms produced by DR are in the 6 2 P excited state, while a small fraction of the atoms produced by the less likely routes along two states of Rb 2 are in the 5 2 P 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.