title: Communication: Selection rules for tunneling splitting of vibrationally excited levels.
abstract: Five symmetry-based selection rules are formulated that relate the tunneling splitting of a vibrationally excited level to that of the ground level in molecules with a symmetric double-minimum potential. The rules, which explain why excited levels frequently have smaller splittings than zero-point levels, are used to interpret the observed and calculated splittings in malonaldehyde.
authors.affiliation: National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada. willem.siebrand@nrc-cnrc.gc.ca
authors.forename: Willem
authors.initials: W
authors.lastname: Siebrand
authors.forename: Zorka
authors.initials: Z
authors.lastname: Smedarchina
authors.forename: Antonio
authors.initials: A
authors.lastname: Fernández-Ramos