Two-dimensional submonolayer of silver nanoparticles was prepared on glass surface by self-assembly method. Double assembly structure of silver nanoparticles was also constructed with 4-aminothiophenol as the linker, forming particle cluster with molecular gap between the particles. Surface plasmon resonance (SPR) of the assembled silver nanoparticles depended on the distance between the particles, the adsorption of molecules, and the assembly structure. The electromagnetic coupling among the particles in the particle monolayer resulted in a blue shift of the SPR band. The adsorption of 4-aminothiolphenol, on the other hand, caused a red shift of the SPR band. Surface-enhanced Raman spectroscopic results demonstrated that the silver nanoparticle cluster with molecular gap between the particles led to a great enhancement of the Raman scattering of the linker 4-aminothiophenol molecules, and larger extent of charge transfer between the 4-aminothiophenol molecules and silver nanoparticles.

Key words: silver nanoparticle, 4-aminothiophenol, self-assembly, surface-enhanced Raman spectroscopy, surface plasmon resonance