Enhanced two-photon absorption property of silver nanoparticle aggregates induced by a thioether derivative

Abstract

A novel thioether derivative with two-photon absorption activity, 4,4'-((4-(dimethylamino)phenyl)methylene)bis (sulfanediyl)dianiline (abbreviated as L), was designed and synthesized, which was used to couple with Ag nanoparticles (Ag NPs, ∼6 nm) to construct L-Ag hybrid particles with L uniformly dispersed on the surface of Ag NPs. The newly-formed hybrid particles self-assembled through L-L interactions between L molecules in one hybrid particle and adjacent particle to from Ag NPs aggregates (100 nm in diameter). By Raman and XPS analysis, the interfacial interaction ‘hot spot’ was determined, which was between thioether group and primary amino group of L molecule and Ag+ ion on the surface of pure Ag NPs. The interfacial interactions between the two components brought about changeable linear optical properties and enhanced nonlinear optical properties, two-photon absorption cross section and two-photon absorption coefficient included. Furthermore, the optical power limiting application of Ag NPs aggregates was also optimized by this means.