Polystyrene beads as probes of the surface-enhanced Raman scattering response characteristics of silver nanorod arrays.

Polystyrene microspheres were used to interrogate the surface-enhanced Raman scattering (SERS) response of silver nanorod (AgNR) array substrates. It has been suggested that enhancement between nanorods is significantly greater than that at the top due to contributing electromagnetic fields from each nanostructure. To test this theory, two different sized fluorescent polystyrene microspheres were used. The SERS intensity of beads small enough to fit within the array was compared with that of larger beads confined to rest on top of the array. Location of the beads within the array was established using optical fluorescence and scanning electron microscopy. The findings presented herein suggest that evaporation of the sample produces a nonuniform distribution of scatterers across the AgNR array and that the enhancement found for beads located on top of the AgNRs was significantly greater than that for beads located within the array.