Femtosecond dynamics and optical nonlinearities of fullerenes and their derivatives

Optical nonlinearities of fullerenes and their derivatives were demonstrated by means of the femtosecond time-resolved optical Kerr effect at a wavelength of 647 nm. From the transient response, which was primarily pulse limited, the dephasing time T2 of all samples has been proved to be much shorter than the laser pulse width. By comparing the optical Kerr effect signals with that of CS2 reference, we acquired large second order hyperpolarizability for C60, C70, C84 and some C60-derivatives. The large and different optical nonlinearities were interpreted using pure ??-conjugated-electron model and the influence of molecular structures.EI01-447-541