Second-Order Nonlinear Optical Scattering Properties of Phosphine-Protected Au20 Clusters

Abstract

We report the first hyperpolarizability of the [Au20(PP3)4]Cl4 cluster (PP3: tris(2-(diphenylphosphino)ethyl)phosphine) using the Hyper-Rayleigh Scattering technique. This is the first determination of nonlinear optical properties of a phosphine-protected "superatomic" gold cluster. Weak contributions of multiphoton-excited fluorescence were observed in the spectral dispersion of the generated light upon excitation at 1300 and 1064 nm. The first hyperpolarizability of the intrinsically chiral cluster is weaker than that of thiolate-protected gold clusters of similar size and inherent chirality.