Surface- and tip-enhanced Raman and LSPR spectroscopies have developed over the past 15 years as unique tools for uncovering the properties of single particles and single molecules that are unobservable in ensemble measurements. Measurements of individual events provide insight into the distribution of molecular properties that are averaged over in ensemble experiments. Raman and LSPR spectroscopy can provide detailed information on the identity of molecular species and changes in the local environment, respectively. In this review a detailed discussion is presented on single-molecule and single-particle Raman and LSPR spectroscopy focusing on the major developments in the fields and applications of the techniques.

Interest in nanotechnology is driven by the unique and novel properties of nanoscale materials such as the strong interaction of metal particles with light, caused by localized surface plasmon resonances (LSPRs). In this perspective article we review and discuss prominent advantages and advances in single particle studies of plasmonic nanostructures. Common techniques and recent improvements in spatial and spectral resolution will first be outlined, covering both far-field and near-field phenomena. Then, new insight and information uniquely obtained from single particle approaches will be overviewed, including several fundamental studies of plasmonic behaviour, as well as applications using single particle tracking and chemical reaction monitoring. Finally, highly interdisciplinary future directions and experiments are discussed.