title: High-resolution vacuum-ultraviolet photoabsorption spectra of 1-butyne and 2-butyne.
abstract: The absolute photoabsorption cross sections of 1- and 2-butyne have been recorded at high resolution by using the vacuum-ultraviolet Fourier-Transform spectrometer at the SOLEIL Synchrotron. Both spectra show more resolved structure than previously observed, especially in the case of 2-butyne. In this work, we assess the potential importance of Rydberg states with higher values of orbital angular momentum, l, than are typically observed in photoabsorption experiments from ground state molecules. We show how the character of the highest occupied molecular orbitals in 1- and 2-butyne suggests the potential importance of transitions to such high-l (l = 3 and 4) Rydberg states. Furthermore, we use theoretical calculations of the partial wave composition of the absorption cross section just above the ionization threshold and the principle of continuity of oscillator strength through an ionization threshold to support this conclusion. The new absolute photoabsorption cross sections are discussed in light of these arguments, and the results are consistent with the expectations. This type of argument should be valuable for assessing the potential importance of different Rydberg series when sufficiently accurate direct quantum chemical calculations are difficult, for example, in the n ≥ 5 manifolds of excited states of larger molecules.
authors.affiliation: Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland.
authors.forename: U
authors.initials: U
authors.lastname: Jacovella
authors.affiliation: STFC, Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD, United Kingdom.
authors.forename: D M P
authors.initials: DM
authors.lastname: Holland
authors.affiliation: Institut des Sciences Moléculaires d'Orsay, UMR 8214, CNRS and Université Paris-Sud, F-91405 Orsay, France.
authors.forename: S
authors.initials: S
authors.lastname: Boyé-Péronne
authors.affiliation: Institut des Sciences Moléculaires d'Orsay, UMR 8214, CNRS and Université Paris-Sud, F-91405 Orsay, France.
authors.forename: B
authors.initials: B
authors.lastname: Gans
authors.affiliation: Synchrotron Soleil, L'Orme des Merisiers, F-91192 Gif-sur-Yvette, France.
authors.forename: N
authors.initials: N
authors.lastname: de Oliveira
authors.affiliation: Synchrotron Soleil, L'Orme des Merisiers, F-91192 Gif-sur-Yvette, France.
authors.forename: D
authors.initials: D
authors.lastname: Joyeux
authors.affiliation: Synchrotron Soleil, L'Orme des Merisiers, F-91192 Gif-sur-Yvette, France.
authors.forename: L E
authors.initials: LE
authors.lastname: Archer
authors.affiliation: Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA.
authors.forename: R R
authors.initials: RR
authors.lastname: Lucchese
authors.affiliation: Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: H
authors.initials: H
authors.lastname: Xu
authors.affiliation: Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: S T
authors.initials: ST
authors.lastname: Pratt