Lambda-like chromophores for chiral non-linear optical materials

The first hyperpolarizability of several ii-like chromophores including Mal achite Green and Brilliant Green were measured by means of Kleinman-disallo wed hyper-Rayleigh (harmonic light) scattering (KD-HRS). Such chromophores are of interest as components of a new class of chiral and axial macroscopi c materials. Light scattering measurements were carried out in both the non -resonant and the anomalous dispersion regime in order to compare experimen tal results with a two-level model that indicates that B-symmetry excited s tates will contribute. Large hyperpolarizabilities were observed in all cas es and evidence that the lowest-lying excited state has B-symmetry was foun d in some molecules. (C) 2001 Elsevier Science B.V. All rights reserved.