Laser Raman spectroscopy at single molecules

摘要

Detecting and characterizing the chemical structure of a single molecule represents the ultimate sensitivity limit in chemical analysis and is of great scientific and practical interest. In this article, we shall introduce a method which combines modern laser spectroscopy with the exciting optical properties of metallic nanostructures. The method allows to detect and to identify a single molecule under ambient conditions using its intrinsic surface-enhanced Raman spectrum. In the experiments, single molecules are attached to silver or gold nanoparticles. In the following, we briefly introduce the physics behind the applied technique of surface enhanced Raman scattering. Single molecule Raman experiments are described including examples for applications in the biomedical field. Prospects and limitations of the new laser spectroscopic method are discussed.