Surface Enhanced Raman Scattering Enhancement Factors:  A Comprehensive Study

Abstract

This paper presents an in-depth study of Surface Enhanced Raman Scattering (SERS) enhancement factors (EFs) and cross-sections, including several issues often overlooked. In particular, various possible rigorous definitions of the SERS EFs are introduced and discussed in the context of SERS applications, such as analytical chemistry and single molecule SERS. These definitions highlight the importance of a careful characterization of the non-SERS cross-sections of the probes under consideration. This aspect is illustrated by experimental results for the non-SERS cross-sections of representative SERS probes along with average SERS EFs for the same probes. In addition, the accurate experimental determination of single molecule enhancement factors is tackled with two recently developed techniques, namely: bi-analyte SERS (BiASERS) and temperaturedependent SERS vibrational pumping. We demonstrate that SERS EFs as low as 10 7 , as opposed to the figure of 10 14 often claimed in the literature, are sufficient for the observation of single molecule SERS signals, with maximum single molecule EFs typically on the order of ∼10 10 .

Raman and Surface Enhanced Raman Signals of the Sensor 1-(4-Mercaptophenyl)-2,4,6-Triphenylpyridinium Perchlorate

“…The methodology used to obtain the enhancement factor (EF) values in SERS and SHINERS spectra has been reported by Le Ru et al 15 and considers the intensity of any band present in both spectra (EF=I SERS /I Raman ).…”

Synthesis of size tunable monodispersed silver nanoparticles and the effect of size on SERS enhancement

“…The Raman enhancement effect in the SERS experiment was determined by the AEF, which is denoted by G, describes the enhancement of the Raman signal per molecule adsorbed on the surface of a SERS-active species (in this case AgNPs) [39,40]. G is calculated as: [36].…”

Beam focusing in reflections from flat subwavelength diffraction gratings

“…In subwavelength regime d < λ neither the first m = 1 nor the higher m > 1 diffraction orders appear, and the reflection and transmission of the zero component m = 0 depend on the averaged characteristics of the grating, as the wave does not distinguish its subwavelength structure. Subwavelength gratings are applied, e.g., for exciting the surface waves: surface plasmons in optics [1], or surface modes of sound waves in acoustics [2], for enhancement of Raman scattering [3], or for reduction of thermo-refractive noise in reflections [4]. Other applications of subwavelength gratings rely on transmission and reflection dependence on polarization and on frequency [5].…”