Isobutyl acetate: electronic state spectroscopy by high-resolution vacuum ultraviolet photoabsorption, He(I) photoelectron spectroscopy and ab initio calculations*
1 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
2 School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
3 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
4 Département de Chimie, Université de Liège, Institut de Chimie – Bât. B6C, 4000 Liège, Belgium
5 ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
6 Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
Received: 31 January 2017
Received in final form: 24 March 2017
Published online: 25 May 2017
The high-resolution vacuum ultraviolet photoabsorption spectrum of isobutyl acetate, C6H12O2, is presented here and was measured over the energy range 4.3–10.8 eV (290–115 nm). Valence and Rydberg transitions with their associated vibronic series have been observed in the photoabsorption spectrum and are assigned in accordance with new ab initio calculations of the vertical excitation energies and oscillator strengths. The measured photoabsorption cross sections have been used to calculate the photolysis lifetime of this ester in the Earth’s upper atmosphere (20–50 km). Calculations have also been carried out to determine the ionization energies and fine structure of the lowest ionic state of isobutyl acetate and are compared with a photoelectron spectrum (from 9.5 to 16.7 eV), recorded for the first time. Vibrational structure is observed in the first photoelectron band of this molecule.
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