Resonance-enhanced time-resolved optical Kerr effect of beta-carotene in solution.

A sharp resonant amplification of the third-order susceptibility of a diluted beta-carotene solution in dodecane is observed by means of the time-resolved optical Kerr effect when the wavelength of the probe is tuned in the range of 490-570 nm. The resonance is well in the red with respect to the 0-0 first electronic transition; some evidence is given of the possible role of higher excited states and of two-photon resonance.