Bi-analyte single molecule SERS technique with simultaneous spatial resolution.

The simultaneous combination on CCD detectors of both spectral and spatial information is used in the framework of the single molecule (SM) bi-analyte Surface-Enhanced Raman Scattering (SERS) technique, to provide a new level of understanding on the origins of SM-spectra, as well as reveal the advantages and limitations of the statistical identification of SM-events. A new and deeper interpretation of the roots of the inhomogeneous broadening of single molecule Raman peaks can be uncovered, as well as the origin of Surface-Enhanced Fluorescence (SEF) emission by single molecules. In this manner, subtler aspects of SM-SERS spectroscopy can be revealed by the additional presence of spatial information on the localization of single molecules producing the signal. The spatial information is normally lost through the standard binning of CCD cameras for spectroscopy, which only emphasizes the spectral dimension of the problem. This novel extension of the bi-analyte SM-SERS method should contribute to the furtherance of the technique, and several of its fundamental aspects are discussed in detail.