Institut des Sciences Moléculaires d'Orsay




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Home > Research Teams > Surfaces, Interfaces, Molecules & 2D Materials (SIM2D)

Surfaces, Interfaces, Molecules & 2D Materials (SIM2D)

The SIREN team investigates the physical and chemical properties of surfaces mainly covered by molecular systems and/or clusters for which we try to measure the structural parameters and understand the mutual interactions. For instance, the absorption of reactive species (H2, H2O, etc.) can lead to a spontaneous nanostructuration. For self-assembled molecular layers, the interactions depend on the density and number of layers. Either we observe directly the organization by STM or GIFAD or we apply molecular spectroscopy (HREELS, SFG) to identify specific molecular terminations, their orientation, and environment. Well controlled low energy electrons are also used to induce energy specific reactions and to graft specific terminations.
These technics described below are now connected together via an ultra-high vacuum tunnel to better combine topology and spectroscopy. The application span astrophysics, radiobiology, thin layer growth, molecular electronics chemical and biological sensors

Fast Atom Diffraction

After discovering that fast (keV) atoms can diffract on crystal surfaces, we have developped the technique. It can image large dimensions of the crystal surface with a resolution reaching 10 pm. The inelastic component highlights surface defects (steps, ad-atoms) and dynamical aspects of the surface (vibrational excitations, electron-hole pair creations..).

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Interfaces, Nanostructures and Interactions Dynamics

Objectives: create metal-molecule ordered héterostructures as well as chalcogenide materials, families of low dimensional materials with novel properties of interest in applications such as molecular electronics. We do this using synchrotron radiation, complemented by scanning tunnelling microscopy and ion scattering.

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Surface chemistry & slow electrons, 0-50eV

Low-energy electron beams of controlled energy make it possible both, to analyse the chemical compositions of surfaces and interfaces, and to induce specific chemical reactions. The aims of the work carried out concern the identification of the species and interaction mechanisms involved, and the quantitative evaluation of the efficiency of the chemical processes induced under radiation.

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Graphene : Molecules & Transport

STM topography and I(V), I(Z) and Z(V) spectroscopies are used to study the atomic-scale structural, electronic and electron transport properties of graphene epitaxially grown on SiC substrates. STM is also used to investigate self-assembling and reactivity of molecules on graphene with the aim to locally modify the electronic properties of graphene.

Techniques: Room temperature STM - STS, UHV, molecular deposition

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Nano-architecture moléculaires et surfaces nanostructurées.

By combining local probe (STM) and electronic spectroscopies (XPS/UPS) the group interest is focused on the study and control of formation of organic molecular layers on surfaces at meso/macro scale and aim at using its experience in chemical reactivity induced nano-structuration of metal surfaces to use them as original substrate morphologies.

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New 2D Materials: silicene, phosphorene, Bismuthene

Silicene forms a buckled honeycomb structure when grown on many surfaces as single layers or nanowires. The first experimental observations (APL 2010, 97, 223109) confirmed the initial theoretical proposals. Self-assembled silicene nanoribbons and silicene sheets deposited on different crystalline surfaces are studied with STM.

Techniques: RT STM - LT STM - Surface X-Ray Diffraction (SXRD) - ALE - Auger Electron Spectroscopy (AES) - LEED - Synchrotron Radiation

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Wide band gap Materials: Diamond, Silicon Carbide, Oxides

Transparent wide band-gap materials play a crucial role in many applications ranging from high power micro-electronics, and opto-electronics ranging from photo-voltaic cells to photo-catalysis. A number of challenges need to be overcome if Diamond, Silicon carbide and oxide materials are to be used nanoscale applications. These include surface preparation and atomic-scale characterisation, efficient doping, conductivity and molecular adsorption.

Techniques: UHV NC AFM - RT STM - LEED - Hydrogen Plasma - Atomic Layer Epitaxy (ALE)

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