Statistics of Single-Molecule Surface Enhanced Raman Scattering Signals:  Fluctuation Analysis with Multiple Analyte Techniques

Abstract

The mathematical background, based on a variation of the principal component analysis (PCA) method, is developed for the understanding of fluctuating multiple analyte single-molecule (SM) surface enhanced Raman scattering (SERS) signals; with emphasis on the bianalyte SERS technique developed recently. The method and its significance are presented to provide a systematic framework with which several aspects of the statistics of SM-SERS signals can be analyzed in general. We also apply the method to a concrete example of bianalyte statistics in silver colloidal solutions and discuss related topics around experimental issues and the interpretation of single-molecule SERS data.

Electrochemical Control of the Time-Dependent Intensity Fluctuations in Surface-Enhanced Raman Scattering (SERS)

“…PCA was used to extract the signal from each component in the complex set of SERS spectra. 41 The histograms in Figure 4 imply the same type of fluctuations that are characteristic of the adsorption of a small number of molecules, as discussed in Figures 2 and 3.…”

“…41 In order to estimate the number of molecules being effectively irradiated in our experiments, we used the adsorption parameter for R6G on Ag colloids determined by Hildebrandt and Stockburger 42 ). For a Langmuir isotherm, the surface coverage (Γ) is simply given by Γ) Γ max · K ads · C in the low concentration limit, where C is the solution concentration of the dye.…”

Ultra‐Sensitive Graphene‐Plasmonic Hybrid Platform for Label‐Free Detection

“…At extreme dilution, the spatial coincidence of an analyte molecule with the hot spots of the hybrid platform will be the key to detect molecular signal. Following the argument of Le Ru and Etchegoin, [35][36][37] the bi-analyte nature of target molecules serves as strong evidence that the spectrum of one certain analyte from an individual pixel is attributed to single molecule. Next, we present spatially resolved Raman data to assess the relative importance of EM and CM to the overall SERS enhancement ( Figure 5 ).…”

“…[32][33][34] Single molecule SERS detection is demonstrated experimentally using a bi-analyte approach. [35][36][37] Furthermore, the high resolution vibrational information provided by SERS enables us to better understand the chemical mechanism, and explore the interaction between molecules and graphene.…”

Coherent anti-Stokes Raman scattering with single-molecule sensitivity using a plasmonic Fano resonance

“…Surfaceenhanced Raman scattering (SERS) [1][2][3] has advanced to the detection limit of individual resonant molecules when the molecule is closely associated with the nanoscale junction between chemically fabricated nanoparticles [4][5][6][7][8][9][10][11][12] . Here two enhancement mechanisms are at play: the enhanced Raman cross-section of a molecule when the excitation laser is resonant with an electronic excitation of the molecule; and the extremely large local electromagnetic (EM) field enhancement generated by optically exciting the collective plasmon mode of the two closely adjacent nanoparticles.…”