Valence shell electronic spectroscopy of isoprene studied by theoretical calculations and by electron scattering, photoelectron, and absolute photoabsorption measurements

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Abstract

The first ab initio calculations (vertical energies and oscillator strengths) are reported for the neutral electronic transitions of isoprene (2-methyl-1,3-butadiene), CH2CHC(CH3)CH2. The VUV photoabsorption spectroscopy of the molecule is presented in the energy range 4.6 to 10.8 eV (270-125 nm) with the highest resolution yet reported above 6.05 eV, revealing new spectral features. Valence and Rydberg transitions have been assigned in accordance with the theoretical results and the associated vibronic series have been analysed. The absolute photoabsorption cross sections at energies below 6.89 eV have been used to calculate the photolysis lifetime of isoprene in the upper stratosphere (20-50 km). Electron energy loss spectroscopy (EELS) measurements have enabled further photoabsorption cross sections to be derived in the range 9-28 eV. The first ab initio calculations have been carried out to determine excitation energies to the lowest energy ionic states of isoprene. The calculations are compared with the He(I) photoelectron spectrum (8 to 17 eV) and new vibrational structure is observed in the first photoelectron band.
Original languageUnknown
Pages (from-to)11219-11231
JournalPhysical Chemistry Chemical Physics
Volume11
Issue number47
DOIs
Publication statusPublished - 1 Jan 2009

Keywords

    Cite this

    @article{333a4f492faa4252b65a0169b26bf75a,
    title = "Valence shell electronic spectroscopy of isoprene studied by theoretical calculations and by electron scattering, photoelectron, and absolute photoabsorption measurements",
    abstract = "The first ab initio calculations (vertical energies and oscillator strengths) are reported for the neutral electronic transitions of isoprene (2-methyl-1,3-butadiene), CH2CHC(CH3)CH2. The VUV photoabsorption spectroscopy of the molecule is presented in the energy range 4.6 to 10.8 eV (270-125 nm) with the highest resolution yet reported above 6.05 eV, revealing new spectral features. Valence and Rydberg transitions have been assigned in accordance with the theoretical results and the associated vibronic series have been analysed. The absolute photoabsorption cross sections at energies below 6.89 eV have been used to calculate the photolysis lifetime of isoprene in the upper stratosphere (20-50 km). Electron energy loss spectroscopy (EELS) measurements have enabled further photoabsorption cross sections to be derived in the range 9-28 eV. The first ab initio calculations have been carried out to determine excitation energies to the lowest energy ionic states of isoprene. The calculations are compared with the He(I) photoelectron spectrum (8 to 17 eV) and new vibrational structure is observed in the first photoelectron band.",
    keywords = "potentials, cations, ab-initio, sets, radical, organic-compounds, volatile, ionization, resonance, perturbation-theory, gaussian-basis, vuv, calculations, photoabsorption, cross-sections, oscillator-strengths, raman",
    author = "Lim{\~a}o-vieira, {Paulo Manuel Assis Loureiro}",
    year = "2009",
    month = "1",
    day = "1",
    doi = "10.1039/b916620c",
    language = "Unknown",
    volume = "11",
    pages = "11219--11231",
    journal = "Physical Chemistry Chemical Physics",
    issn = "1463-9076",
    publisher = "ROYAL SOC CHEMISTRY",
    number = "47",

    }

    TY - JOUR

    T1 - Valence shell electronic spectroscopy of isoprene studied by theoretical calculations and by electron scattering, photoelectron, and absolute photoabsorption measurements

    AU - Limão-vieira, Paulo Manuel Assis Loureiro

    PY - 2009/1/1

    Y1 - 2009/1/1

    N2 - The first ab initio calculations (vertical energies and oscillator strengths) are reported for the neutral electronic transitions of isoprene (2-methyl-1,3-butadiene), CH2CHC(CH3)CH2. The VUV photoabsorption spectroscopy of the molecule is presented in the energy range 4.6 to 10.8 eV (270-125 nm) with the highest resolution yet reported above 6.05 eV, revealing new spectral features. Valence and Rydberg transitions have been assigned in accordance with the theoretical results and the associated vibronic series have been analysed. The absolute photoabsorption cross sections at energies below 6.89 eV have been used to calculate the photolysis lifetime of isoprene in the upper stratosphere (20-50 km). Electron energy loss spectroscopy (EELS) measurements have enabled further photoabsorption cross sections to be derived in the range 9-28 eV. The first ab initio calculations have been carried out to determine excitation energies to the lowest energy ionic states of isoprene. The calculations are compared with the He(I) photoelectron spectrum (8 to 17 eV) and new vibrational structure is observed in the first photoelectron band.

    AB - The first ab initio calculations (vertical energies and oscillator strengths) are reported for the neutral electronic transitions of isoprene (2-methyl-1,3-butadiene), CH2CHC(CH3)CH2. The VUV photoabsorption spectroscopy of the molecule is presented in the energy range 4.6 to 10.8 eV (270-125 nm) with the highest resolution yet reported above 6.05 eV, revealing new spectral features. Valence and Rydberg transitions have been assigned in accordance with the theoretical results and the associated vibronic series have been analysed. The absolute photoabsorption cross sections at energies below 6.89 eV have been used to calculate the photolysis lifetime of isoprene in the upper stratosphere (20-50 km). Electron energy loss spectroscopy (EELS) measurements have enabled further photoabsorption cross sections to be derived in the range 9-28 eV. The first ab initio calculations have been carried out to determine excitation energies to the lowest energy ionic states of isoprene. The calculations are compared with the He(I) photoelectron spectrum (8 to 17 eV) and new vibrational structure is observed in the first photoelectron band.

    KW - potentials

    KW - cations

    KW - ab-initio

    KW - sets

    KW - radical

    KW - organic-compounds

    KW - volatile

    KW - ionization

    KW - resonance

    KW - perturbation-theory

    KW - gaussian-basis

    KW - vuv

    KW - calculations

    KW - photoabsorption

    KW - cross-sections

    KW - oscillator-strengths

    KW - raman

    U2 - 10.1039/b916620c

    DO - 10.1039/b916620c

    M3 - Article

    VL - 11

    SP - 11219

    EP - 11231

    JO - Physical Chemistry Chemical Physics

    JF - Physical Chemistry Chemical Physics

    SN - 1463-9076

    IS - 47

    ER -