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01/2003: pages 121 - 144; , ISBN: 9783527600809
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ABSTRACT: Surface-enhanced Raman scattering (SERS) is a spectroscopic technique which combines modern laser spectroscopy with the exciting optical properties of metallic nanostructures, resulting in strongly increased Raman signals when molecules are attached to nanometre-sized gold and silver structures. The effect provides the structural information content of Raman spectroscopy together with ultrasensitive detection limits, allowing Raman spectroscopy of single molecules. Since SERS takes place in the local fields of metallic nanostructures, the lateral resolution of the technique is determined by the confinement of the local fields, which can be two orders of magnitude better than the diffraction limit. Moreover, SERS is an analytical technique, which can give information on surface and interface processes. SERS opens up exciting opportunities in the field of biophysical and biomedical spectroscopy, where it provides ultrasensitive detection and characterization of biophysically/biomedically relevant molecules and processes as well as a vibrational spectroscopy with extremely high spatial resolution. The article briefly introduces the SERS effect and reviews contemporary SERS studies in biophysics/biochemistry and in life sciences. Potential and limitations of the technique are briefly discussed.
Journal of Physics Condensed Matter 04/2002; 14(18):R597. · 2.55 Impact Factor
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ABSTRACT: We review surface-enhanced linear and nonlinear Raman scattering experiments on molecules and single wall carbon nanotubes
attached to colloidal silver and gold clusters. Surface-enhanced hyper-Raman scattering and surface-enhanced anti-Stokes Raman
scattering from pumped vibrational levels are studied as two-photon excited Raman processes where the scattering signal depends
quadratically on the excitation laser intensity. The experimental results are discussed in the framework of strongly enhanced
electromagnetic fields predicted for such cluster structures in so-called “hot spots.” The electromagnetic enhancement factors
for Stokes, pumped anti-Stokes, and hyper-Raman scattering scale as theoretically predicted, and the field strengths in the
hot spots, it is inferred, are enhanced of the order of 103. From our experiments we claim a very small density of hot spots (0.01 % of the cluster surface) and lateral confinement
of the strong field enhancement within domains that can be as small as 10 nm.
Effective cross sections of the order of 10-16 cm2 and 10-42 cm4 s for Stokes and pumped anti-Stokes scattering, respectively, are adequate for one-and two-photon Raman spectroscopy of single
molecules.
12/2001: pages 227-249;
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ABSTRACT: This report describes surface-enhanced Stokes and anti-Stokes Raman scattering of molecules in aqueous colloidal silver solution using non-resonant near-infrared excitation. We demonstrate that extremely large surface-enhanced Raman cross sections of the order of 10−16 cm2 per molecule can be combined with favorable conditions for excitation and collection of Raman scattered light provided by a Raman microscope to achieve single molecule sensitivity. Surface-enhanced Raman spectroscopy will be compared with fluorescence spectroscopy as a tool for single molecule detection.
Bioimaging 05/2001; 6(2):104 - 110.
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ABSTRACT: Surface-enhanced Raman scattering (SERS) at an extremely high enhancement level opens up interesting and new spectroscopic possibilities. The effect combines the sensitivity of fluorescence spectroscopy with the high structural information content of Raman spectroscopy, and can be used for single molecule detection and identification. This paper reports single molecule detection and identification of ‘non-absorbing’ molecules in colloidal silver solutions using near-infrared excited surface-enhanced Stokes and anti-Stokes Raman scattering. SERS enhancement factors of the order of 1014–1015 or, in other words, effective Raman cross-sections between 10-16 and 10-15 cm2/molecule result in a significant transfer of ground state population to the first excited vibrational state due to the strong Raman process. This allows the observation of v=1 to v=2 (‘hot’) vibrational transitions in SERS additionally to v=0 to v=1 transitions ‘normally’ probed in a Raman experiment. © 1998 John Wiley & Sons, Ltd.
Journal of Raman Spectroscopy 05/1999; 29(8):743 - 747. · 3.09 Impact Factor
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ABSTRACT: Surface-enhanced hyper-Raman scattering and surface-enhanced anti-Stokes Raman scattering were studied as potential tools for non-linear single-molecule Raman spectroscopy. Experiments were performed using near-infrared excitation on crystal violet adsorbed on colloidal silver or gold clusters. Strong enhancement factors on the order of 1020 were inferred from hyper-Raman scattering experiments on colloidal silver. Such extremely high enhancement factors overcome the inherently weak nature of the effect, and surface-enhanced hyper-Raman scattering appears on comparable intensity levels as surface-enhanced Raman scattering. Surface-enhanced anti-Stokes Raman scattering starts from vibrational levels, that are populated by the very strong surface-enhanced Raman process. Thus, the anti-Stokes Raman scattering signal depends quadratically on the excitation laser intensity. For the first time, surface-enhanced anti-Stokes and Stokes Raman scattering was detected from single molecules on colloidal gold clusters.
Chemical Physics.
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Physical Review Letters. 78(9):1667.
