Studies of third-order nonlinear optical properties of C60 by the optical Kerr effect

60 at 1.064 μm is determined by the optical Kerr effect in toluene solution. Values of -6.5×10^-33 esu and 2.0×10^-32 esu for the real and imaginary parts of γ, respectively, are obtained. Based on the experimental results and symmetry constraint, it is concluded that a three-level model is not adequate to describe the third-order nonlinearity of C₆₀. It is also inferred that the non-resonant γ of C₆₀ should be positive in sign, which is in agreement with reported off-resonant measurements of γ of C₆₀ by third-harmonic generation. Received: 3 September 1997/Revised version: 1 December 1997