Sub-picosecond studies of the third-order optical nonlinearities of C-60-toluene solutions

The third-order optical nonlinearities of C-60-toluene solutions are studied employing transient degenerate four-wave mixing (DFWM) and z-scan techniques using 0.5 ps laser pulses at 497 nm. The concentration dependence of the chi((3)) of the solution and both the sign and the magnitude of the real and imaginary parts of the third-order susceptibility of C-60 are obtained. The molecular second hyperpolarizability gamma of C-60 is found to be (2.3 +/- 0.6) x 10(-32) esu. The role of nonlinear absorption and its influence on the DFWM signal is discussed. Finally a comparison of our experimental data with other data in the literature is given.