title: Vibrational fine structure of C5 via anion slow photoelectron velocity-map imaging.
abstract: High-resolution anion photoelectron spectra of cryogenically cooled C5(-) clusters are reported using slow photoelectron velocity-map imaging spectroscopy. We resolve vibronic transitions to the ν2 stretching mode and multiply excited ν5, ν6, and ν7 bending modes of neutral C5 with significantly higher accuracy than previous experiments. Weak transitions to Franck-Condon (FC) forbidden singly excited bending modes are made possible by Herzberg-Teller coupling between electronic states of the neutral cluster. In addition, we resolve vibrational fine structure corresponding to different angular momentum states of multiply excited bending modes. The observation of this multiplet structure, some of which is FC forbidden, is attributed to Renner-Teller coupling between vibrational levels in the C5(-) ground electronic state.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA.
authors.forename: Marissa L
authors.initials: ML
authors.lastname: Weichman
authors.forename: Jongjin B
authors.initials: JB
authors.lastname: Kim
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Neumark