Understanding the formation of aligned, linear arrays of Ag nanoparticles

We report the self-assembly of aligned arrays of silver nanoparticles governed by a reaction-diffusion-precipitation process. The average 2 μm wide bands containing nanoparticles which are ∼160 nm in diameter are highly periodic with ∼0.9-3 μm spacing. Morphological and analytical characterization of the particles has provided crucial information for the formulation of a series of reactions explaining the band formation. We propose that the silver/silver oxide colloids in the bands turn into elemental silver particles upon UV illumination. A self-assembly process, the Liesegang phenomenon, was applied to align silver nanoparticles in highly periodic linear arrays and two alternative mechanisms were proposed to explain the process.