Third-order resonant nonlinearities of some organometallic salts containing metal dithiolene

The third-order optical nonlinearities of the organometallic salts, [CpFe(η-CH)]n [M(mnt)2] and [CpFe(η-C6H 6)]n [M(dmit)2] (M = Ni, Pd, Pt, Cu or Co; Cp = η-Cyclopentadienyl; H2mnt = maleonitriledithiole; H2dmit = 4,5-dimercapto-1,3-dithiole-2-thione; n = 1 or 2), were studied by means of degenerate four-wave-mixing (DFWM) technique at 532 nm. Their second hyperpolarizablities are in the order of 10−30esu. The results suggest that the observed optical nonlinearities mainly come from the contribution of the metal dithiolene anions, and contribution from resonant enhancement plays a dominant role in determining the intensity of nonlinearity of this class of materials.