Plasmon resonance tuning in Ag nanoparticles arrays grown on ripple patterned templates

A bottom-up approach to grow highly ordered self-assembled silver nanoparticles arrays on ripple patterns produced by low energy ion irradiation is reported. The advantage of this approach over other self-assembling or lithographic methods is the flexibility to tune the array periodicity down to 20 nm with inter-particle gaps as low as 5 nm along the ripples. The silver nanoparticle arrays grown on these rippled surfaces are optically anisotropic, i.e. they exhibit a direction dependent shift in their localised surface plasmon resonance. The reason for the observed anisotropy is a direction dependent plasmonic field coupling. In this way the capability to tune the plasmon resonance by varying the ripple wavelength is demonstrated. (C) 2012 Elsevier B.V. All rights reserved.