title: Valence and Ionic Lowest-Lying Electronic States of Isobutyl Formate Studied by High-Resolution Vacuum Ultraviolet Photoabsorption, Photoelectron Spectroscopy, and Ab Initio Calculations.
abstract: The highest resolution vacuum ultraviolet photoabsorption spectrum of isobutyl formate, C5H10O2, yet reported is presented over the energy range 4.5-10.7 eV (275.5-118.0 nm) revealing several new spectral features. Valence and Rydberg transitions and their associated vibronic series observed in the photoabsorption spectrum have been assigned in accordance with new ab initio calculations of the vertical excitation energies and oscillator strengths. Calculations have also been carried out to determine the ionization energies and fine structure of the lowest ionic state of isobutyl formate and are compared with a newly recorded photoelectron spectrum (from 9.0 to 27.0 eV). The value of the first ionization energy was determined to be 10.508 eV (adiabatic) and 10.837 eV (vertical). New vibrational structure is observed in the first photoelectron band, predominantly resulting from C-O and C═O stretches of the molecule. The photoabsorption cross sections have been used to calculate the photolysis lifetime of isobutyl formate in the upper stratosphere (20-50 km), indicating that the hydroxyl radical processes will be the main loss process for isobutyl formate.
authors.affiliation: †Department of Control and Power Engineering, Faculty of Ocean Engineering and Ship Technology, Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk, Poland.|‡Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom.
authors.forename: M A
authors.initials: MA
authors.lastname: Śmiałek
authors.affiliation: §Department of Theoretical Physics and Quantum Information, Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Łabuda
authors.affiliation: §Department of Theoretical Physics and Quantum Information, Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Guthmuller
authors.affiliation: ∥ISA, Department of Physics and Astronomy, Aarhus University, DK 8000 Aarhus C, Denmark.
authors.forename: S V
authors.initials: SV
authors.lastname: Hoffmann
authors.affiliation: ∥ISA, Department of Physics and Astronomy, Aarhus University, DK 8000 Aarhus C, Denmark.
authors.forename: N C
authors.initials: NC
authors.lastname: Jones
authors.affiliation: ⊥Canadian Light Source Inc., 44 Innovation Boulevard, Saskatoon, Saskatchewan S7N 2V3, Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: MacDonald
authors.affiliation: ⊥Canadian Light Source Inc., 44 Innovation Boulevard, Saskatoon, Saskatchewan S7N 2V3, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Zuin
authors.affiliation: ‡Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom.
authors.forename: N J
authors.initials: NJ
authors.lastname: Mason
authors.affiliation: ‡Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom.|#Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors.forename: P
authors.initials: P
authors.lastname: Limão-Vieira
mesh_terms: D005561:Formates / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D008956:Models, Chemical; D056951:Photoelectron Spectroscopy; D013056:Spectrophotometry, Ultraviolet; D014618:Vacuum; D014732:Vibration
chemical_list: D005561:Formates; D007477:Ions