Vibrational autoionization in PF3: Doing violence to the propensity rule

The photoionization spectrum of PF+3 in its threshold region displays two prominent progressions of autoionization peaks. When these are analyzed, together with earlier photoabsorption studies and a photoelectron spectrum, they lead to the conclusion that vibrational autoionization is occurring, with Δν≤−13. This conclusion stands in sharp contrast with the current theory of vibrational autoionization, which predicts a propensity rule Δν=−1. Other examples from the recent literature are summarized, to suggest that a more general theory of vibrational autoionization is required.