Projet de thèse en Physique - Cergy
Sous la direction de François Dulieu et de Liv Hornekaer.
Thèses en préparation à Cergy-Pontoise , dans le cadre de ED SI - Sciences et Ingénierie , en partenariat avec Laboratoire d'Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères (laboratoire) depuis le 06-10-2012 .
Ce programme scientifique a pour but de mieux comprendre l'interaction de l'hydrogène et de l'oxygène sur des surfaces carbonées, en particulier le graphite, le graphène et les PAHs.
Experimental investigations of Oxygen and Hydrogen interactions on carbonaceous surfaces
Context of the thesis The present thesis application is a coordinated experimental project between Aarhus University (AU) and Cergy Pontoise University (CPU), carried out within the frame of the Dept. of Physics and Astronomy, AU and LERMA laboratories, CPU. It takes place thanks to the european ITN LASSIE. The scientific leading is jointly exercised by Pr Liv Hornekaer and Pr François Dulieu , also advisors of the thesis. Scientific context and purposes The scientific program aims at achieving better understanding of the interaction of hydrogen and oxygen on carbonaceous surfaces, in particular graphite, graphene and polycyclic aromatic hydrocarbons. The project encompasses reactions between both weakly bound (physisorbed) and strongly bound (chemisorbed) species. Physisorption is important for the development of graphene based nanotechnologies like NEMS (Nano-ElectroMechanical-Systems), while chemisorption is relevant for nanoelectronic devices (Balog et al. 2010) and for plasma wall interactions in nuclear fusion facilities. Both regimes play important roles in solid-state astrochemistry. The project will focus on dynamical processes that may lead to synthesis of new species such as water or carbon dioxide, as well as on chemical functionalization of the substrate. The experiments will involve the FORMOLISM and/or VENUS experimental set-up at LERMA in Cergy, Paris Observatory: a cold (6-380 K) sample in a UHV chamber is exposed to molecular or atomic beams of hydrogen and/or oxygen (Dulieu et al. 2010). Evolution of the incident or nascent populations, probed by mass or laser spectroscopies (Amiaud et al. 2008), provide insight in the dynamical processes taking place on the surface: adsorption, desorption, reaction. IR spectroscopy can inform on the possible functionnalization of the substrate. Complementary to these techniques, investigations with Scanning Tunneling Microscopy (STM) combined with Thermal Desorption Spectroscopy will be carried out at the Surface Dynamics Laboratory at the Dept. of Physics and Astronomy, AU. Such investigations will provide additional information on the functionnalization of the substrate, as well as on the structure of remaining reaction products on the surface. Special focus will be aimed at the morphology of water ices formed in situ on the carbonaceous surfaces. The expected scientific results include synthesis of water on graphite and graphene, efficiency of formation, as well as a description of the chemical network, and a search for possible oxidation of the graphite basal plane.