Two-photon absorption and Raman spectra of C-60-2-thioxo-1,3-dithiole cycloadduct

Two-photon absorption (TPA) at lambda = 532 nm of C-60-2-thioxo-1,3-dithiol e cycloadduct vs, applied hydrostatic pressure p up to 20 GPa and temperatu re T in the range 77-300 K was measured. Correlation between the observed T PA dependencies and the Raman active modes behaviour has been revealed. Usi ng theoretical Green function calculations and the observed experimental de pendencies, we discuss the essential contribution of vibrational harmonic a nd anharmonic contributions to the output nonlinear optical susceptibilitie s. Comparing the obtained results with those of C-60, we have unambiguously shown that the observed behaviors are connected with the adding of the 1,3 -dithiole core. (C) 1999 Elsevier Science B.V. All rights reserved.