Surface‐enhanced Raman spectroscopy: a brief retrospective

Abstract The electromagnetic theory of surface‐enhanced Raman spectroscopy (SERS), despite its simplicity, can account for all major SERS observations, including: the need for a nanostructured material as the SERS‐active system; the observation that some metals form good SERS‐active systems while others do not; the observation that strongly interacting metal nanoparticles result in very much more effective SERS‐active systems; the observed polarization sensitivity shown by nanoparticle aggregates; and the optical behavior of nanostructured metals in the absence of a molecular adsorbate. By extending the ideas inherent in the electromagnetic model one can also understand the seminal features reported for…