The Jahn–Teller effect in the 3 pe ′ Rydberg state of H 3 : review of experimental and ab initio determinations

Abstract

The dissociative recombination (DR) of H ions with electrons, producing neutral atomic and molecular fragments, is driven primarily by the vibronic Jahn–Teller (JT) interaction between the electronic components of the pe ′ e − –H collision (Rydberg) channel. The JT parameters characterizing this interaction are therefore of great interest as they are required for the theoretical predictions of the DR cross section. In this contribution, we review various determinations of these quantities that have been made previously, based both on spectroscopic studies of 3 pe ′ Rydberg-excited H 3 states, and on the analysis of the corresponding ab initio H 3 Rydberg potential surfaces near the conical intersection (D 3h symmetry) for n =3−5. The highly correlated theoretical 3 pe ′ potential surfaces of Mistrík et al. are used for a new determination of both the linear and quadratic JT terms.