Surface Enhanced Raman Scattering by Metal Spheres. I. Cluster Effect

Inoue, Masahiro; Ohtaka, K.

doi:10.1143/jpsj.52.3853

Cited by 183 publications

(138 citation statements)

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“…[5][6][7] Liao et al 5 prepared in-line aligned nanorod arrays on lithographically produced templates, while Martínes et al 6 and Wachter et al 7 produced side-by-side aligned nanorod arrays by oblique deposition. Taking into account the gap enhancement in the local field, 8 in-line alignment of the nanorods is more desirable than side-by-side alignment. However, even today, it is difficult to produce sub-micrometer patterns over large areas at low cost.…”

Section: Introductionmentioning

confidence: 99%

Au Nanorod Arrays Tailored for Surface-Enhanced Raman Spectroscopy

et al. 2007

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IntroductionFor applying local field enhancement arising from local plasmons present in noble metal nanoparticles to biochemical sensors, such as surface-enhanced Raman scattering (SERS) sensors, it is important to control both the shape and the arrangement of the nanoparticles.1 It is well known that wellordered 2D periodic arrays of triangular nanoparticles prepared by nanosphere lithography (NSL) show plasma resonance within a rather narrow wavelength region, and the sharp corners of the triangles result in strong SERS.2 Although NSL enables the size of the nanoparticles to be tuned, the number density of the nanoparticles is geometrically fixed. Some applications, such as Raman imaging, may require more SERS-active spots to improve the space resolution. In addition, it is difficult to tune the lowest order of the local plasma resonance to the near-infrared (NIR) region, which is appropriate for biological applications. 3A drastic enhancement in the local field is considered to also occur at the ends of elongated nanoparticles. 4 In fact, for light in the visible to NIR region, SERS has been observed on arrays of elongated Ag nanoparticles, or so-called nanorods, whose widths are in the range of tens of nanometers and whose aspect ratios are 2 -5. 5-7 Liao et al. 5 prepared in-line aligned nanorod arrays on lithographically produced templates, while Martínes et al. 6 and Wachter et al. 7 produced side-by-side aligned nanorod arrays by oblique deposition. Taking into account the gap enhancement in the local field, 8 in-line alignment of the nanorods is more desirable than side-by-side alignment. However, even today, it is difficult to produce sub-micrometer patterns over large areas at low cost.Gold nanorods are also attracting much interest, since chemically stable Au is considered to be preferred to Ag for the material of the SERS substrates. In addition to lithographically produced Au nanorod arrays, 9 random aggregates of Au nanorods produced by chemical routes [10][11][12] are extensively investigated. However, it is not easy to immobilize the Au nanorods uniformly in isolation with each other.Recently, we demonstrated the direct formation of Ag nanorods with quasi-parallel major axes on a template layer of SiO2 having a strongly anisotropic surface morphology by using a dynamic oblique deposition (DOD) technique. 13 These Ag nanorods show excellent SERS properties. 14,15 In this study, we report that physically self-assembled Au nanorod arrays show fairly highly sensitive SERS properties that are comparable with those of Ag. ExperimentalThe preparation method of Au nanorod arrays is basically the same as that of Ag nanorod arrays reported in our previous papers.14,15 Briefly, template layers of SiO2 were prepared on a glass substrate by the serial bideposition (SBD) technique, which is a version of the vacuum evaporation technique. During SBD, the deposition angle, αSiO 2 , measured from the surface normal was fixed to 78.6˚, while the azimuth was rapidly changed by 180˚ with each deposition of a 10-nm-t...

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Section: Introductionmentioning

confidence: 99%

Au Nanorod Arrays Tailored for Surface-Enhanced Raman Spectroscopy

et al. 2007

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“…Indeed, one can liken the metallic clusters to tiny antennas that enhance and transmit the Raman-scattered light. The enhancement depends on the type of metal, its degree of roughness-the sizes and shapes of the clusters that form-and the frequency of the incident light [54][55][56]. In this scenario, the precise and tight control of the morphology of metallic structures at the nanoscale is a major requisite for the design of efficient SERS substrates.…”

Section: Discussionmentioning

confidence: 99%

“…For certain architectures, this response can be extremely strong, with |E| 2 enhancement up to six orders of magnitude [54,56,[62][63][64][65][66][67]. Recalling that the Raman signal in SERS substrates scales with the fourth power of the electric field, similar geometries would guarantee a Raman increment of the order of 10 12 , which is a giant enhancement of the spectroscopy signal, which would be sufficient to reveal, in theory, the signature of a single molecule.…”

Section: Discussionmentioning

confidence: 99%

The Five Ws (and one H) of Super-Hydrophobic Surfaces in Medicine

et al. 2014

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Super-hydrophobic surfaces (SHSs) are bio-inspired, artificial microfabricated interfaces, in which a pattern of cylindrical micropillars is modified to incorporate details at the nanoscale. For those systems, the integration of different scales translates into superior properties, including the ability of manipulating biological solutions. The five Ws, five Ws and one H or the six Ws (6W), are questions, whose answers are considered basic in information-gathering. They constitute a formula for getting the complete story on a subject. According to the principle of the six Ws, a report can only be considered complete if it answers these questions starting with an interrogative word: who, why, what, where, when, how. Each question should have a factual answer. In what follows, SHSs and some of the most promising applications thereof are reviewed following the scheme of the 6W. We will show how these surfaces can be integrated into bio-photonic devices for the identification and detection of a single molecule. We will describe how SHSs and nanoporous silicon matrices can be combined to yield devices with the capability of harvesting small molecules, where the cut-off size can be adequately controlled. We will describe how this concept is utilized for obtaining a direct TEM image of a DNA molecule. OPEN ACCESSMicromachines 2014, 5 240

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“…Localized surface plasmons, i.e., resonant charge-density oscillations confined to metal nanostructures, can efficiently convert propagating light into nanoscale confined and strongly enhanced optical fields, which generate high-intensity gradients responsible for the trapping mechanism. Among the huge variety of plasmonic nanostructures, a pair of metal nanoparticles separated by a nanometric gap produces an intense optical spot that is approximately two orders of magnitude smaller than the wavelength of the incident light [10][11][12], and it enables the optical trapping and confinement of dielectric nanoparticles such as polystyrene and living biological specimens with reduced laser intensity compared with conventional optical tweezers [6,7]. Furthermore, the nanogap structure was shown to trap metal and semiconductor nanoparticles with 10-nm dimensions [8,9].…”

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confidence: 99%

Optical trapping through the localized surface-plasmon resonance of engineered gold nanoblock pairs

Tanaka¹,

Sasaki²

2011

Opt. Express

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Abstract:We have investigated the plasmonic trapping of dielectric nanoparticles by using engineered gold nanoblock pairs with ~5-nm gaps. Pairs with surface-plasmon resonance peaks at the incident wavelength allow the trapping of 350-nm-diameter nanoparticles with 200 W/cm 2 laser intensities, and their plasmon resonance properties and trapping performance are drastically modified by varying the nanoblock size of ~20%. In addition, plasmon resonance properties of nanoblock pairs strongly depend on the direction of the linear polarization of the incident laser, which determines the trapping performance. ©2011 Optical Society of America References and links1. K. Okamoto and S. Kawata, "Radiation force exerted on subwavelength particles near a nanoaperture," Phys.Rev. Lett. 83(22), 4534-4537 (1999). 2. P. C. Chaumet, A. Rahmani, and M. Nieto-Vesperinas, "Optical trapping and manipulation of nano-objects with an apertureless probe," Phys.

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Surface Enhanced Raman Scattering by Metal Spheres. I. Cluster Effect

Cited by 183 publications

References 14 publications

Au Nanorod Arrays Tailored for Surface-Enhanced Raman Spectroscopy

Au Nanorod Arrays Tailored for Surface-Enhanced Raman Spectroscopy

The Five Ws (and one H) of Super-Hydrophobic Surfaces in Medicine

Optical trapping through the localized surface-plasmon resonance of engineered gold nanoblock pairs

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