In-line aligned and bottom-up Ag nanorods for surface-enhanced Raman spectroscopy

Suzuki, Motofumi; Maekita, Wataru; Wada, Yoshinori; Nakajima, K.; Kimura, Kenji; Fukuoka, Tokuma; Mori, Yasushige

doi:10.1063/1.2205149

Cited by 61 publications

(60 citation statements)

References 15 publications

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“…2(i). Here, the morphology and optical properties of the Ag nanorod arrays are basically the same as those reported in our previous study, 14 and are similar to those of the Au nanorod arrays in sample F. Some researchers may be under the impression that SERS on Au nanoparticles is 1 -2 orders of magnitude smaller than that on Ag nanoparticles. However, this is correct only for spherical nanoparticles that resonate in the visible wavelength region, since the interband transition in this region disturbs the plasma resonance in the case of Au.…”

Section: Methodssupporting

confidence: 71%

“…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. …”

mentioning

confidence: 93%

“…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-thick layer.…”

Section: Methodsmentioning

confidence: 99%

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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: Methodssupporting

confidence: 71%

mentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

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Au Nanorod Arrays Tailored for Surface-Enhanced Raman Spectroscopy

et al. 2007

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“…The optical property of silver nanowires depends on their diameter and length. [26][27][28] When the nanowires are relatively short, two absorption bands appear due to the transverse and longitudinal modes of the dipolar plasmon. The transverse mode is parallel to the short axis of the wires and its absorption band appears in the short wavelength region; on the other hand, the longitudinal mode is parallel to the long axis and its plasmon wavelength is shifted toward red with increasing length of the nanowires.…”

Section: Introductionmentioning

confidence: 99%

Diameter Effect of Silver Nanorod Arrays to Surface-enhanced Raman Scattering

Gu¹,

Kim²,

Yoon³

et al. 2014

Bulletin of the Korean Chemical Society

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The effect the diameter of silver nanorod arrays whose distance between the nanorods was uniform at 65 nm have on Surface-enhanced Raman Scattering (SERS) has been studied by varying the diameter from 28 to 51 nm. Nanorod length was fixed at approximately 62 nm, which is the optimum length for SERS by excitation with a 632.8 nm laser line. The transverse and longitudinal modes of the surface plasmon of these silver nanorods were near 400 and 630 nm, respectively. The extinction of the longitudinal mode increased with increasing nanorod diameter, while the transverse mode did not change significantly. High-quality SERS spectra of p-aminothiophenol and benzenethiol adsorbed on the tips of the silver nanorods were observed by excitation with a 632.8 nm laser line. The SERS enhancement increased with increasing nanorod diameter. We concluded that the SERS enhancement increases when the diameter of silver nanorods is increased mainly by increasing the excitation efficiency of the longitudinal mode. The enhancement factor for the silver nanorods with a 51 nm diameter was approximately 2 × 10 7 .

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“…Although the advanced functionalities of OAD films are well understood in academia, there seems to be prejudice in the industry that OAD thin films are neither durable nor reproducible. However, in the past few years, very fortunately, new products produced by the OAD technique have appeared on the market, including a substrate for surface-enhanced Raman spectroscopy [6][7][8] and a low-reflectivity wire-grid polarizer. 9,10 In this article, we discuss the practicability of OAD thin films and examples of the products produced by the OAD technique.…”

Section: Introductionmentioning

confidence: 99%

Practical applications of thin films nanostructured by shadowing growth

Suzuki

2013

J. Nanophoton

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Abstract. Even prior to the recent advent of advanced top-down processes, shadowing growth by oblique angle deposition (OAD) has long been providing self-assembled nanostructures over much larger areas for much lower costs. In the past two decades, significant progress has been made in the development of well-controlled three-dimensional nanomorphologies such as zigzags and helixes. Much effort has been put into theoretical and numerical understanding of the growth mechanism to improve morphology. Many researchers in academia have been investigating useful properties of nanocolumnar thin films in their laboratories. However, most companies seem hesitant to introduce OAD techniques into the factory, owing to the prejudice that the OAD thin films are neither durable nor reproducible. The progress in OAD technology for practical applications is reviewed and discussed.

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In-line aligned and bottom-up Ag nanorods for surface-enhanced Raman spectroscopy

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Cited by 61 publications

References 15 publications

Au Nanorod Arrays Tailored for Surface-Enhanced Raman Spectroscopy

Au Nanorod Arrays Tailored for Surface-Enhanced Raman Spectroscopy

Diameter Effect of Silver Nanorod Arrays to Surface-enhanced Raman Scattering

Practical applications of thin films nanostructured by shadowing growth

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