Relating SERS Intensity to Specific Plasmon Modes on Sphere Segment Void Surfaces

Colloidal-crystal templated electrodeposition can be used to fabricate sphere segment void (SSV) substrates that show large, reproducible enhancements in surface-enhanced Raman spectroscopy (SERS). These SSV substrates support a variety of plasmon modes and can be fully characterized by white light dispersion measurements allowing the direct identification of the modes predicted by computational models of the nanoscale optical fields. Comparing plasmon absorption with SERS enhancements as a function of sphere segment void diameter and metal thickness for a series of SSV substrates allows the identification of the specific plasmon modes, which give rise to large SERS enhancements at different laser wavelengths and in different media. The measured SERS intensities show direct correlation to the plasmonic modes of the structures providing a guide to the design of efficient surfaces for SERS.