Raman scattering single molecule detection

Kneipp K, Wang Y, Kneipp H, Itzkan I, Dasari R R and Feld M S 1996 Approach to single molecule detection using surface-enhanced Raman scattering ICORS 98 XVth Int. Conf on Raman Spectroscopy ed S A Asher and P B Stein (New York Wley) pp 636-7... 

Kneipp, K., Wang, Y., Kneipp, H., Perelman, L. T., Itzkan, I., Dasari, R. R. and Eeld, M. S. (1997) Single molecule detection using surface-enhanced Raman scattering (SERS). Phys. Rev. Lett., 78, 1667-1670. 

Kneipp K., Kneipp H., Deinum G., Itzkan I., Dasari R.R., Feld M. S., Single-molecule detection of a cyanine dye in silver colloidal solution using near-infrared surface-enhanced Raman scattering, Appl. Spectrosc. 1998 52 175-178. 

Koo, T. W., Chan, S., and Berlin, A. A. 2005. Single-molecule detection of biomolecules by surface-enhanced coherent anti-Stokes Raman scattering. Opt. Lett. 30(9) 1024—26. 

The extremely small cross sections for conventional Raman scattering, typically 10 111 to 10-25 cm2/molecule has in the past precluded the use of this technique for single-molecule detection and identification. Until recently, optical trace detection with single molecule sensitivity has been achieved mainly using laser-induced fluorescence [14], The fluorescence method provides ultrahigh sensitivity, but the amount of molecular information, particularly at room temperature, is very limited. Therefore, about 50 years after the discovery of the Raman effect, the novel phenomenon of dramatic Raman signal enhancement from molecules assembled on metallic nanostructures, known as surface-enhanced Raman spectroscopy or SERS, has led to ultrasensitive single-molecule detection. 

Le Ru EC, Etchegoin PG, Meyer M (2006) Enhancement factor distribution around a single surface-enhanced Raman scattering hot spot and its relation to single molecule detection. J Chem Phys 125 (20) 204701... 

Surface enhanced resonance Raman scattering (SERRS) [1-3] is a highly sensitive technique, so sensitive in fact that single molecule detection has previously been reported [4, 5]. It is a very attractive technique for the detection of biomolecules because it produces molecularly specific spectra which make it feasible to easily identify the components of a mixture in a single analysis without extensive separation procedures [6]. 

The Raman techniques combined with AEM microscopic imaging, as for instance TERS (tip-enhanced Raman scattering) spectroscopy [27], allow to analyze surface nanostructures beyond the diffraction limit, but the cost of the instrumental apparatus is not affordable for any research laboratory. Therefore, in this chapter, the results obtained with those techniques will not be presented, though they increased Raman enhancement factors by up to lO, with the possibility of single-molecule detection. Conversely, confocal micro-Raman apparatus is affordable to every research group allowing SERS investigations with more comparable results. 

To examine the role of the LDOS modification near a metal nanobody and to look for a rationale for single molecule detection by means of SERS, Raman scattering cross-sections have been calculated for a hypothetical molecule with polarizability 10 placed in a close vicinity near a silver prolate spheroid with the length of 80 nm and diameter of 50 nm and near a silver spherical particle with the same volume. Polarization of incident light has been chosen so as the electric field vector is parallel to the axis connecting a molecule and the center of the silver particle. Maximal enhancement has been found to occur for molecule dipole moment oriented along electric field vector of Incident light. The position of maximal values of Raman cross-section is approximately by the position of maximal absolute value of nanoparticle s polarizability. For selected silver nanoparticles it corresponds to 83.5 nm and 347.8 nm for spheroid, and 354.9 nm for sphere. To account for local incident field enhancement factor the approach described by M. Stockman in [4] has been applied. To account for the local density of states enhancement factor, the approach used for calculation of a radiative decay rate of an excited atom near a metal body [9] was used. We... 

C.J.L. Constantino, T. Lemma, P.A. An-tunes, and R. Aroca, Single-Molecule Detection Using Surface-Enhanced Resonance Raman Scattering and Langmuir-Blodgett Monolayers, Anal. Chem. 73, 3674 (2001)... 

K. Kneipp, Y. Wang, H. Kneipp, LT. Pe-relman, 1. Itzkan, R. Dasari, and M S. Feld, Single-Molecule Detection Using Sur-face-Enhanced Raman Scattering (SERS), Phys. Rev. Lett. 78, 1667 (1997)... 

B. Tolaieb, C.J.L. Constantino, and R.F. Aroca, Surface-Enhanced Resonance Raman Scattering as an Analytical Tool for Single Molecule Detection, Analyst 129,... 

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