[show abstract][hide abstract] ABSTRACT: We report the synthesis, the photophysical and the two-photon absorption (2PA) properties of a series of octupolar bipyrimidine-based ligands incorporating N-substituted amines as terminal donor groups. The effect of replacing phenylvinylene [capital Pi]-conjugated linkers by fluorenylvinylene ones was also investigated. The linear absorption spectrum of these compounds is dominated by an intensive charge transfer band which is sensitive to the N-substitution and the [capital Pi]-bridge nature. The excitation anisotropy spectrum indicates that this band encompasses multiple S0[rightward arrow]Sn transitions whose occurrence is well rationalized on the basis of the Frenkel exciton model. The 2PA spectrum also corroborates the presence of several electronic transitions. In apolar or moderatly polar medium, excited ligands mainly deactivate through a highly emissive intramolecular charge transfer (ICT) state localized within a single branch of the chromophore. In highly polar medium, the solvent-induced s
[show abstract][hide abstract] ABSTRACT: Deep-UV lithography using high-efficiency phase mask has been developed to print 100 nm period grating on sol-gel based thin layer. High efficiency phase mask has been designed to produce a high-contrast interferogram (periodic fringes) under water immersion conditions for 244 nm laser. The demonstration has been applied to a new developed immersion-compatible sol-gel layer. A sol-gel photoresist prepared from zirconium alkoxides caped with methacrylic acids was developed to achieve 50 nm resolution in a single step exposure. The nanostructures can be thermally annealed into ZrO<sub>2</sub>. Such route considerably simplifies the process for elaborating nanopatterned surfaces of transition metal oxides, and opens new routes for integrating materials of interest for applications in the field of photocatalysis, photovoltaic, optics, photonics or microelectronics.
[show abstract][hide abstract] ABSTRACT: DUV interferometric lithography and diblock copolymer self-organization have successfully been combined to provide a simple and highly collective nanopatterning technique enabling the organization of nanoparticles over several orders of magnitude, from nanometre to millimetre. The nanostructural changes at the surface of the polymer film after thermal annealing have been monitored by AFM and the process parameters optimized for obtaining a long-range organization of the lamellar domains. In particular, the impact of the annealing conditions and geometric parameters of the substrate patterns have been investigated. The nanopatterns resulting from the lamellar demixion of (PS-b-MMA) were used for a controlled deposition of nanoparticles. The affinity of the hydrophobic particles for the PS block was demonstrated, opening new doors towards the preparation of high-density arrays of nanoparticles with potential applications in data storage.
[show abstract][hide abstract] ABSTRACT: The mechanism of radical polymerization photoinitiated by a near-infrared absorbing indotricarbocyanine (HITC) was investigated using an indirect kinetics method based on the photobleaching dynamics of the dye. Despite similar photophysical features in glycerol and in pentaerythritol triacrylate monomer, HITC undergoes a very fast photobleaching in the acrylate resin which leads to photopolymerization at high power regime. The addition of an amine induces the decrease of photopolymerization threshold by a factor 5 with unexpected dye regeneration. These effects were correlated to the reactivity of the reduced and oxidized forms of HITC produced via triplet–triplet annihilation and ground state quenching processes.
Chemical Physics Letters 01/2011; 515(1):91-95. · 2.15 Impact Factor