Laser-activated surface-enhanced Raman scattering substrates capable of single molecule detection

Surface-enhanced Raman scattering (SERS) substrates were obtained through silver reduction on and by nanostructured Si films. The absence of any chemical agents on the Ag nanoparticle surfaces allows analyte adsorption and SERS detection immediately with spotting. These SERS substrates have the further unique and useful attribute of being laser activated; i.e., laser impingement causes Ostwald ripening and formation of aggregates (e.g., dimers and trimers), which are essential for single molecule detection. Single molecule detection of fluorescein characterized with intermittent spectral fluctuations as well as a dramatic decrease in inhomogeneous Raman linewidth was demonstrated.