Excited-state enhancement of optical nonlinearity in C60

We report our observation of the excited-state enhancement of the nonlinear optical response in C60 toluene solutions by simultaneous resonant pumping. The dynamics of this enhancement was studied and two different relaxation process were obtained, which can be attributed to the singlet and triplet excited states of C60 molecule. The (gamma) xxxx value of the singlet and triplet excited states were calculated to be enhanced by over three and two orders of magnitude respectively, compared with that of the ground state, while no enhancement was observed in the (gamma) xyyx component.