UFR de Physique

Propositions de stages en laboratoire -- M2

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Characterization of molecular complexes between terpenoids and hydrogen sulfide by quantum chemical calculations and microwave spectroscopy

  • Option International « Atmospheric Environnement » du parcours Lumière-Matière
  • Laboratoire: Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM)
  • Responsable du stage: DREAN pascal (pascal.drean@univ-lille.fr, 03.20.43.49.05)
  • Co-responsable(s): HUET Thérèse, GOUBET Manuel
  • Mots clés: Microwave spectroscopy – quantum chemical calculations – molecular complexes.
  • Fiche complète en PDF : Fiche complète en PDF

In the troposphere, monoterpenoids (ketones and aldehydes) are formed by oxydation of monoterpenes widely emitted by trees and plants, for instance the α and β pinenes or limonene. They possess an oxygen atom which acts as a proton acceptor. Molecules with a proton donor, like H2O or H2S, can link to terpenoids to form molecular complexes. So far, we have characterized a lot of hydrates (up to 3 water molecules around the substrate) but almost nothing is known about complexes with H2S. We aim at knowing if it is possible to characterize such complexes and find structures close to those observed with H2O. Structures of different complexes and conformers are first optimized by quantum chemical calculations. Experimentally, the complexes are formed by a supersonic expansion of a gas mixture (terpenoid – H2S – carrier gas) in a cavity where they are probed by microwave spectroscopy. The analysis of the spectra give rotational constants which are compared to those obtained by quantum chemical calculations. Molecular structures can then be assigned to the different observed species without any doubt. The work is made of an experimental part (record of the spectra) and of a theoretical part (analysis of the spectra, quantum chemical calculations).