NLO effect as a sensitive tool for determination of phase transition in C/sub 60/-2-thioxo-1, 3-dithiole and in C/sub 60/-TTF derivatives

Chemical modifications of C/sub 60/ are interesting owing to potential improvement of their stability and processability, as well as their optical nonlinearities. This study concerns fullerenes functionalized with 2-thioxo-1, 3-dithiole (CA) and tetrathiafulvalene (TTF) cycloadducts in the solid state. Photoinduced nonlinear effects in these compounds are investigated using nonlinear optical techniques such as photoinduced optical second harmonic generation (PISHG), two-photon absorption (TPA) and linear electrooptics effects (Pockels effects) in order to determine phase transitions in the mentioned compounds.