In Situ Observation of Surface-Enhanced Raman Scattering From Silver Nanoparticle Dimers and Trimers Fabricated Using AFM Manipulation

The generation of surface-enhanced Raman scattering (SERS) was directly observed in situ during the fabrication of Ag nanoparticle (AgNP) dimers and trimers using atomic force microscopy (AFM) manipulation, and the size of the SERS hot spot was estimated using the super-resolution imaging technique. SERS from 4,4’-bipyridine was observed upon the fabrication of the AgNP dimers and trimers using AFM manipulation. Then, the SERS spots were analyzed by fitting with the point spread function for super-resolution imaging. The distribution of the centroid position of the SERS spot from the AgNP dimer was 9 nm along the x-axis and 8 nm along the y-axis, which represent the size of the SERS hot spot. The same technique was applied to the AgNP trimer. The obtained results are important not only for the SERS technique but also for other plasmon enhancement techniques which are useful in a wide range of research areas.