The development of nano-structured plasmonic composite by two-step ion-exchange processes

Surface enhanced Raman scattering (SERS) active substrate was fabricated using Ag⁺-Na⁺ ion-exchange technique. A thin layer of Aluminum was subsequently deposited which provides electrons and effectively promotes the reduction of the Ag⁺ ions in the follow-up Na⁺-K⁺ ion exchange process. The extinction spectrum exhibits a broadened and red-shifted peak indicating that the filling fraction was increased, and the distribution of the particle size and shape are multi-dispersed. The trend can be explained by Maxwell Garnett theory enabling molecular sensing over a wide spectral range. The spectral fingerprint of Rhodamine 6G molecules is successfully detected in the Raman spectrum.