Structures of silver with peculiar characteristics are the focus of a paper published in Langmuir, Vol 24, No 13, 2008.
Examining a monolayer of silver with surface enhanced Ramen spectography, patterns are observed to form with repeating structures in the range of 150 to 900 nanometers. These structures form a series of circular voids along the surface of a silver film, with each void bumping up against 6 neighboring circular voids. This hexagonal “honeycomb” pattern extends indefinitely in 2 dimensions along the surface of the film. Images of this structure are included in the published document, which is available online here.
These silver films are created using an electrodeposition technique detailed in the paper.
Authored by Mamdouh Abdelsalam, Philip N. Bartlett, Andrea E. Russell, Jeremy J. Baumberg, Ernesto J. Calvo, Nicolás G. Tognalli, and Alejandro Fainstein, here is a segment from the abstract:
In situ electrochemical surface enhanced Raman spectra (SERS) for an immobilized monolayer of a flavin analogue (isoalloxazine) at nanostructured silver surfaces are reported. [ … ] The nanostructured silver surfaces are produced by electrodeposition through colloidal templates to produce thin (<1μm) films containing close-packed hexagonal arrays of uniform 900 nm sphere segment voids. The sphere segment void (SSV) structured silver surfaces are shown to be ideally suited to in situ electrochemical SERS studies at 633 nm, giving stable, reproducible surface enhancements at a range of electrode potentials…