Surface-enhanced Raman Scattering Effect Research Articles

A Mini Review on Surface-Enhanced Raman Scattering based Nanoclusters for Sensing and Imaging Applications

Background: The invention of enhanced Raman scattering by adsorbing molecules on nanostructured metal surfaces is a milestone in the development of spectroscopic and analytical techniques. Important experimental and theoretical efforts were geared towards understanding the Surface Enhanced Raman Scattering effect (SERS) and evaluating its significance in a wide range of fields in different types of ultrasensitive sensing applications. Methods: Metal nanoclusters have been widely studied due to their unique structure and individual properties, which place them among single metal atoms and larger nanoparticles. In general, the nanoparticles with a size less than 2 nm is defined as nanoclusters (NCs) and they possess distinct optical properties. In addition, the excited electrons from absorption bands results in the emission of positive luminescence associated to the quantum size effect in which separate energy levels are produced. Results: It is demonstrated that fluorescent based SERS investigations of metal nanoparticles have showed more photostability, high compatibility, and good water solubility, has resulted in high sensitivity, better imaging and sensing experience in the biomedical applications. Conclusion: In the present review, we report recent trends in the synthesis of metal nanoclusters and their applications in biosensing and bio-imaging applications due some benefits including cost-effectiveness, easy synthesis routes and less consumption of sample volumes. Outcomes of this study confirms that SERS based fluorescent nanoclusters could be one of thrust research areas in biochemistry and biomedical engineering.

Effect of Temperature on the Surface Enhanced Raman Scattering Effect of Silver Substrate

Effect of Temperature on the Surface Enhanced Raman Scattering Effect of Silver Substrate

Synthesis of GO/Au/Ag Nanocomposite with Excellent Surface Enhanced Raman Scattering Effect

In this work, a nanocomposite (GO/Au/Ag) containing graphene oxide (GO) and Au/Ag nanoparticles was fabricated by in situ reduction for improved manipulation of their SERS effect. The uniform dispersion of Au/Ag nanoparticles were successfully generated on GO. Rhodamine 6G (R6G) as a Raman probe was used to investigate the SERS effect. Owing to the synergistic effect of the high localized surface plasmon resonance of Au/Ag, and chemical enhancement of GOs, the Raman intensities of R6G on GO/Au/Ag is several times as high as that on Au/Ag or GO/Au. GO/Au/Ag nanocomposites showed excellent Raman enhancement and appeared to be a kind of valuable material with potential application in SERS detection.

Determination on Origination of Surface Enhanced Raman Scattering Effect on Nano ZnO Substrate

Determination on Origination of Surface Enhanced Raman Scattering Effect on Nano ZnO Substrate

Multifunctional Nanocomposite with Magnetism, Thermosensitivity and Surface Enhanced Raman Scattering Effect.

Multifunctional Fe3O4 @poly(N-isopropylacrylamide-co-acrylamide), Au (Fe3O4 @PNIPAM-AAM, Au) composite with magnetism, themosensitivity, surface enhanced Raman scattering (SERS) effect and drug delivery ability was successfully prepared. Transmittance measurements at 350 nm confirm the composite has a lower critical solution temperature (LCST) about 41 degrees C. Due to the network structure of PNIPAM-AAM, the composite is also an ideal drug carrier. An encapsulation efficiency of 90 wt% was demonstrated by using Ampicillin as a model drug. The drug release process was closely related with the environmental temperature, which was dramatically accelerated at temperature above LCST, and a much greater release amount was achieved. The Raman enhancement effect of such versatile composite was evaluated by using crystal violet (CV) as a probe molecule, which verified the composite is an effective SERS substrate.

Surface Enhanced Raman Scattering Effect of Au-Ag Alloy Films Based on Kretschmann Configuration†

The surface enhanced Raman scattering(SERS) effect of Au-Ag alloy films was investigated,using a 532 nm laser source and the Kretschmann configuration. The experimental results indicate that when the incidence angle of the p-polarized beam meets the surface plasmon resonance(SPR) condition,the intensities of Raman peaks for Nile Blue molecules immobilized on the Au-Ag alloy film reaches maxima,being almost 2times as high as those achieved with the pure gold layer. Gold nanoparticles(GNP) modification of the Au-Ag alloy films resulted in more than 3 times increase in Raman peak intensity. With the GNP-modified Au-Ag alloy film the Raman peaks are 2 times higher than those with the GNP-modified pure gold layer. The Raman signals detected with the probe placed below the prism substrate are completely non-polarized,but those detected along the reflected light beam on the side of the prism are p-polarized due to the SPR-coupled directional emission of Raman light excited in the evanescent-field region. The work demonstrated that the Au-Ag alloy films are advantageous over the conventional gold films for surface plasmon enhanced Raman spectroscopy.

Surface enhanced Raman scattering effect of CdSe/ZnS quantum dots hybridized with Au nanowire

Functionalized CdSe/ZnS quantum dots (QDs) were attached to the surface of Au nanowire (NW). Analysis of optical absorption spectra disclosed surface plasmon bands of Au NWs at 562 and 627 nm and showing an overlap with the QD absorption band. Micro Raman spectra (λex = 514 nm) of the QDs/Au single NW exhibited surface enhanced Raman scattering (SERS) peaks at 180, 205, and 277 cm−1, corresponding to surface, longitudinal, and transverse optical phonon modes, respectively. From time-resolved fluorescence spectra, the exciton lifetime of QDs decreased after hybridization with Au NW due to the energy transfer, supporting the SERS effect.

Distance dependence of the Surface Enhanced Raman Scattering effect observed in amorphous TiO 2 on nanostructured gold

Plasmon resonance of gold nanoparticles is responsible of the electromagnetic (EM) Surface Enhanced Raman Scattering (SERS) effect. Interaction of an amorphous matrix with a SERS substrate was studied. Thin films with different thickness of amorphous TiO 2 coated on a Klarite® substrate show a 100 times enhancement of the Raman signal. Distance dependence of the SERS interaction was shown to be less than 60 nm.

Signal enhancement in nano-Raman spectroscopy by gold caps on silicon nanowiresobtained by vapour–liquid–solid growth

Silicon nanowires grown by the vapour–liquid–solid growth mechanism with gold as the catalyst show goldcaps ∼50–400 nm in diameter with an almost ideal hemispherical shape atop a silicon column. These goldcaps are extremely well suited for exploiting the tip or surface enhanced Raman scatteringeffects since they assume the right size on the nanometre scale and a reproducible, almostideal hemispherical shape. On attaching a nanowire with a gold cap to an atomic forcemicroscopy (AFM) tip, the signal enhancement by the gold nanoparticle can be used tospatially resolve a Raman signal. Applications of this novel nanowire based technical tipenhanced Raman scattering solution are widespread and lie in the fields of biomedical andlife sciences as well as security (e.g. detection of bacteria and explosives) and in the field ofsolid state research, e.g. in silicon technology where the material composition, doping,crystal orientation and lattice strain can be probed by Raman spectroscopy. A prerequisitefor obtaining this spatial resolution in nano-Raman spectroscopy is the attachment of ananowire with a gold cap to an AFM tip. This attachment by welding a nanowire ina scanning electron microscope to an AFM tip is demonstrated in this paper.

Surface Enhanced Raman Scattering Effects of Silver Colloids with Different Shapes

By solution-based method, three kinds of silver colloids, self-assembled nanowires, triangular nanoplates and quasispherical nanoparticles, have been synthesized. TEM studies revealed that they exposed different crystal planes, such as {111} crystal planes to triangular nanoplates, mainly {100} and {111} planes to self-assembly nanowires. Hereby, do the distinct shapes and crystal planes have an impact on the surface enhanced Raman scattering (SERS)? The great differences of the SERS spectra of rhodamine B at these Ag colloids confirmed that the shapes and crystal planes of silver have great effect on Raman enhancement, especially the crystal planes.