LAboratoire de Spectrochimie Infrarouge et Raman – UMR 8516
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Séminaire du Pr. Rosana Mariel Romano

Universidad Nacional de La Plata, Facultad de Ciencias Exactas, Departamento de Química, CEQUINOR (UNLP-CONICET), Argentina
Photoionization and photofragmentation studies using synchrotron radiation

The interaction of a molecule with electromagnetic radiation can produce a series of different processes, starting for the absorption of a photon. If the incident photon has enough energy to promote one electron to an unoccupied molecular orbital, in a process known as resonant photoexcitation, the molecule will access an electronic excited state. If the energy of the incident photon is sufficiently high, one electron will be ejected from the molecule, in an ionization process. After photoionization of a molecule, different electronic relaxation mechanisms may be feasible, like fluorescence or Auger processes, usually followed by fragmentation of the molecule.Synchrotron facilities constitute ideal light sources for the study of resonant photoexcitation and photoionization processes, as they provide electromagnetic radiation in a wide spectral region and with a high flux and brilliance. Coincidence techniques, that allow detecting electrons and ions originated in a same event, constitute a useful tool for the study of the dynamics of the fragmentation. From the analysis of the shape and slope of the coincidence islands in a bidimensional spectrum, in which two ions are detected in coincidence with the ejected photoelectron, the photofragmentation mechanisms can be proposed. Some examples of photoionization and photofragmentation on molecules with atmospheric interest, performed mainly at the Brazilian Synchrotron Light Laboratory (LNLS), will be presented.

Le séminaire aura lieu le 20.09.2013 à 10h15
Université Lille 1, Amphithéâtre CERLA