Enhanced Raman Scattering in the Near Field of a Scanning Tunneling Tip—An Approach to Single Molecule Raman Spectroscopy

Abstract

In the near field of an illuminated scanning probe tip with a dimension much smaller than a wavelength of the incident light a field enhancement is possible. This effect is similar to the field enhancement on small metal particles investigated in SERS (Surface Enhanced Raman Spectroscopy). In this article a formerly developed and successfully applied BEM (Boundary Element Method) calculation of the electric potential and field is used to compute respective values of an experimental setup arranged by Pettinger et al. which is similar to our experiments focussing on single molecule Raman spectroscopy. The calculated field enhancement factors are compared with the experimentally determined. The results show high electric field enhancement factors in the vicinity of the metallic tip.