Molecular First Hyperpolarizability Data for Lanthanate Complexes Containing the Hemicyanine Chromophore

Abstract

The molecular nonlinear optical polarizability, or first hyperpolarizability β, of four lanthanate complexes containing the hemicyanine 1-hexadecyl-4-{2-[4-(dimethylamino)phenyl]ethenyl}pyridinium chromophore has been determined with high precision. The experimental measurement of the phase shift and the demodulation between immediate hyper-Rayleigh scattering and time-delayed multiphoton fluorescence as a function of modulation frequency allows for the simultaneous data analysis of phase and demodulation toward precise values for fluorescence-free hyperpolarizability, multiphoton fluorescence contribution, and fluorescence lifetime. One order of magnitude improvement in precision is obtained with respect to the earlier analysis of demodulation data only. This level of precision has been used to show the relative impact of f-orbital filling and ligands on the molecular second-order nonlinear optical response of lanthanate complexes containing a hemicyanine chromophore. Implications for the earlier conclusions about better film formation for lanthanate complexes are discussed.