Dispersion of the third-order nonlinearity of a metallo-organic compound

We present a study of the third-order nonlinearity of a ferrocene derivative of a 2-amino-1,2,3-triazol-quinone system [2-(yliminomethylferrocenyl)naptho-1,2,3-triazole-4,9-dione] in solution. The z-scan technique with a tunable 10 ps laser source allowed the resolution of the absorptive and refractive contributions to the nonlinearity at several wavelengths near resonance. The nonlinear response is attributed to the metal-ligand charge transfer that gives rise to the absorption spectrum features. The absorptive contribution changes from saturable to two-photon absorption going away from resonance, vanishing at lambda = 560 nm, which is important for applications based on nonlinear refractive effects. The nonlinear refractive index n(2) remains positive and finite throughout the spectral range investigated. (C) 2003 Elsevier B.V. All rights reserved.