3D-conjugated systems based on oligothiophenes and phosphorus nodes

3D-conjugated systems based on oligothiophene segments grafted on a phosphorus or on a phosphine oxide node have been synthesized. Under Stille coupling conditions, bromide terminated thienyl phosphine derivatives undergo a breaking of the phosphorus–carbon bond attributed to a ligand exchange with the Pd catalyst. The electronic properties of the new compounds have been analyzed by UV-vis and fluorescence spectroscopy and cyclic voltammetry

Are social networking sites information sources? Informational purposes of high-school students in using SNSs

Although social networking sites such as Facebook or Twitter are widely used by teenagers, to date, research has focused on their social uses. This research sought to investigate the ways in which high school students (15–19 years) use such sites in order to find information. It highlights the importance of considering how young people may use social networking sites for everyday life information as well as for academic and school-oriented information. Findings from a web-based survey of students from the UK, France, Thailand and Denmark show that social networking sites are information sources for most teenagers, especially for information related to social activities. Although academic information seeking was not among the most common reasons for using them, the findings indicate that they are used by many students for such purposes, as well as for everyday life information seeking

Raman spectroscopy study of compositional inhomogeneity in lithium tantalate crsytals

International audienc

Analyse de la ŕeponse electro-optique temporelle : Application a differents cristaux organiques, inorganiques et organo-mineraux

International audienc

Frequency and wavelength dependences of electro-optic coefficients in inorganic crystals

International audienceThe frequency dependence of electro-optic co- efficients in congruent and stoichiometric LiNbO3 , LiTaO3 , β-BaB2O4 and KTiOPO4 was determined and compared to each other for the first time in a wide frequency range from DC up to 150 MHz. The measurements have been investigated as a function of laser wavelength from 0.5 to 1.3 µm. Clamped and unclamped electro-optic coefficients as well as the acoustic contribution have been established for each crystal