Radiative decay of the HeH+(b 3 Sigma +) molecular ion

The rate of the radiative decay of the HeH{sup +}({ital b}{sup 3}{Sigma}{sup +}) molecular ion has been investigated. At infinite internuclear separation the {ital b}{sup 3}{Sigma}{sup +} electronic state dissociates to form metastable atomic helium He(2{sup 3}{ital S}) and a proton H{sup +}. The optically allowed electronic transition to the lowest triplet HeH{sup +}({ital a}{sup 3}{Sigma}{sup +}) state which dissociates to He{sup +}(1{ital s}) and H(1{ital s}) was considered. This transition can lead to the population of metastable triplet ({ital a}{sup 3}{Sigma}{sup +}) states in beams of HeH{sup +} ions. {copyright} {ital 1996 The American Physical Society.}