Nanohybrides pour l’excitation multiphotonique/Nanohybrids for multiphoton excitation – NEM

The principal motivation of the present research program is development of a new approach for fabrication and assembly of nano-hybrid systems consisting of a semiconducting metal oxide core with enhanced and controlled multi-photon absorption and functional organic molecules attached to the core surface. The electronics properties of both components will be modified for the best matching of their electronic energy levels, using previously elaborated by us synthetic procedures. Within the nanohybrids, the inorganic core will function like an antenna collecting irradiation in near IR spectral range and transferring the respective doubled or tripled energy to the functional organics. This is an innovative project which proposes the pioneering approach to study nanohybride architecture for various applications involving multiphoton light excitation. The general physical principle of the applications is based on charge transfer under photoexcitation. The result of semiconducting nanoparticle (NP) photoexcitation is formation of electron ' hole pairs. Consequently, following irradiation, the NP act as either the electron or hole donor. Organic molecules connected to the NP surface can scavenge photo-generated holes or electrons. Charge transfer will thus provide considerable spatial separation between the photo-generated positive and negative charges. Localization of the corresponding charge on the adsorbed functional molecules can activate their function (fluorophoric, electrochromic, etc.). The present research program will also provide hitherto missing data necessary to practically design and fabricate functional nanohybrid materials for applications based on multi-photon laser excitation. We will develop: i) optimized synthesis of metal oxide nanoparticles with controlled electronic properties by laser ablation in non-aqueous solvents containing organic functional surface modifiers; ii) synthesis of a variety of new functional organic molecules capable of reversible charge transfer conversions and high affinity toward the metal oxide NP. iii) investigation of the electronic properties of new developed nanohybrid materials aimed at optimization of their properties for further use in applications like two photon bio-imaging and volume information storage. The project will be realized in strong interdisciplinary collaboration between material physicist, organics chemists and physical chemists specialised in IR spectroscopy and in laser time resolved spectroscopy.