Lifetime as well as transition probabilities of the first p-excited states of neon<sup>+</sup>, argon<sup>+</sup>, and krypton<sup>+</sup> have been calculated.
S. H. KOOZEKANANI and G. L. TRUSTY, "Lifetime and Transition Probabilities of np4 (n+1)p States of Ne II, Ar II, and Kr II," J. Opt. Soc. Am. 59, 1281-1284 (1969)