Single molecule SERS: Perspectives of analytical applications

Recent developments in SERS (surface-enhanced Raman scattering) and SERRS (surface-enhanced resonance Raman scattering) spectroscopy are related to the discovery of its single molecule sensitivity. The achievement of single molecule level of SERS and/or SERRS spectral detection is understood to be conditioned by localization of detected molecules into unusually strong nanoscale-localized optical fields (dubbed hot spots). Recent calculations predict SERS enhancement factors as high as I x 10(15) for certain chromophoric molecules located in the hot spot between two Ag nanoparticles [P. Johansson, H. Xu, M. Kall, Phys. Rev. B 72 (2005) 035427.]. Owing to a combination of single molecule sensitivity with the fingerprint selectivity inherent to vibrational spectroscopy, single molecule SERS spectroscopy can potentially offer unprecedented possibilities of analytical applications. (C) 2006 Elsevier B.V. All rights reserved.