title: The electronic states of pyridine-N-oxide studied by VUV photoabsorption and ab initio configuration interaction computations.
abstract: The first vacuum-ultraviolet absorption spectrum of pyridine-N-oxide has been obtained, and has led to the identification of nearly 30 Rydberg states. These states were identified by use of the vibrational envelope ("footprint") of the UV-photoelectron spectrum, and are based on the first to the third ionization energies (IE). The adiabatic IE order, central to the Rydberg state symmetry identification, is confirmed by multi-configuration SCF calculations as: 1(2)B1 < 1(2)B2 < 1(2)A2 < 2(2)B1. Several excited valence state equilibrium structures were determined by multi-configuration SCF and coupled cluster procedures. Multi-reference multi-root CI was used to calculate both Rydberg and valence state vertical excitation energies and oscillator strengths, which were correlated with the experimental measurements.
authors.affiliation: School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, Scotland, United Kingdom. m.h.palmer@ed.ac.uk
authors.forename: Michael H
authors.initials: MH
authors.lastname: Palmer
authors.forename: Søren Vrønning
authors.initials: SV
authors.lastname: Hoffmann
authors.forename: Nykola C
authors.initials: NC
authors.lastname: Jones
authors.forename: Elliott R
authors.initials: ER
authors.lastname: Smith
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Lichtenberger
mesh_terms: D004583:Electrons; D011725:Pyridines / Q000737:chemistry*; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet
chemical_list: D011725:Pyridines; C013229:pyridine N-oxide