VIBRATIONAL STATE DEPENDENCE OF AND D ASYMMETRY PARAMETERS FOR THE HOMO PHOTOELECTRON BAND OF METHYLOXIRANE (Abstract/Poster in convegno)

Type
Label
  • VIBRATIONAL STATE DEPENDENCE OF AND D ASYMMETRY PARAMETERS FOR THE HOMO PHOTOELECTRON BAND OF METHYLOXIRANE (Abstract/Poster in convegno) (literal)
Anno
  • 2008-01-01T00:00:00+01:00 (literal)
Alternative label
  • G. Contini, N. Zema, S. Turchini, D. Catone, T. Prosperi, V. Carravetta, P. Bolognesi, L. Avaldi, V. Feyer (2008)
    VIBRATIONAL STATE DEPENDENCE OF AND D ASYMMETRY PARAMETERS FOR THE HOMO PHOTOELECTRON BAND OF METHYLOXIRANE
    in Società Italiana di Luce di Sicrotrone - XVI Congresso, Palermo, Italia, 26-28/06/2008
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • G. Contini, N. Zema, S. Turchini, D. Catone, T. Prosperi, V. Carravetta, P. Bolognesi, L. Avaldi, V. Feyer (literal)
Note
  • Poster (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • CNR-ISM, Via Del Fosso del Cavaliere 100, I-00133 Roma, Italy CNR-IPCF, via Moruzzi 1, I-56124 Pisa, Italy CNR-IMIP, CP10, I-00016 Monterotondo Scalo, Italy CNR-IMIP, CP10, I-00016 Monterotondo Scalo, Italy and Sincrotrone Trieste, Area Science Park, I-34012 Basovizza, Trieste, Italy (literal)
Titolo
  • VIBRATIONAL STATE DEPENDENCE OF AND D ASYMMETRY PARAMETERS FOR THE HOMO PHOTOELECTRON BAND OF METHYLOXIRANE (literal)
Abstract
  • The effects of the vibrational excitations in the ionic state on the ? and D asymmetry parameters of the highest occupied molecular orbital (HOMO) photoelectron spectrum of gas phase methyloxirane molecule have been studied. The ? angular asymmetry and D dichroic asymmetry parameters of the HOMO band have been experimentally investigated with vibrational resolution using synchrotron radiation. A theoretical calculation of the Franck-Condon (FC) factors between vibrational ground state and different ionic vibrational states, in the Born-Oppenheimer harmonic approximation, has been performed in order to gain information on the vibrational states mainly involved in the HOMO photoelectron band. The general good agreement between theoretical and experimental results allows a reliable assignment of the major features. The computed FC factors distribution reveals that only a small number of vibrational modes are significantly activated in the photoelectron process. The dependence of the ? and D asymmetry parameters as a function of the ionisation energy is experimentally observed and interpreted as dependent on different final vibrational states. Larger D values are observed in the spectral region where transitions with small vibrational quantum numbers (0 or 1) are mainly involved; smaller D values are found, instead, when transitions with large vibrational quantum number are involved. It is proposed to attribute this effect to the different mean molecular geometries of the final vibrational ionic state, i.e. to the different mean internuclear distances at which the transitions occur. This contribution reports, for the first time, the experimental evidence of the dependence of the dichroic D parameter on the vibrational excitation of the ion in a photoelectron valence spectrum. (literal)
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