Unusual optical properties of the Au/Ag alloy at the matching mole fraction

Nishijima, Yoshiaki; Akiyama, Seishiro

doi:10.1364/ome.2.001226

Cited by 68 publications

(83 citation statements)

References 34 publications

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“…The longer wavelengths up to 15 000 nm were then extrapolated using the Drude model. 31,32 The reflection spectra of the reference mirrors are shown in the supplementary material. The setup used for the acquisition of the light scattering spectra comprised a 1.5-in.-diameter integrating sphere (Infragold GPS-IG, Labsphere, North Sutton, US) and a collimated halogen lamp that was used as a light source.…”

Section: B Characterizationmentioning

confidence: 99%

Anti-reflective surfaces: Cascading nano/microstructuring

Nishijima¹,

Komatsu²,

Ota³

et al. 2016

APL Photonics

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The creation of anti-reflective surfaces is reliant on the engineering of the surface textures and patterns to enable efficient trapping or transmission of light. Here we demonstrate anti-reflective layers composed of hierarchical nano/microscale features that are prepared on Si using a combination of wet and dry etching processes, and which are both scalable and affordable. The performance of the structured surfaces was tested through optical measurements of the reflectance, transmittance, and scattering spectra from the visible to mid-infrared wavelength regions, and the results were verified using numerical simulations to identify the performance of the textured anti-reflective layers. The anti-reflective properties of the layers were shown to be dramatically improved by the composite nanostructured surfaces over a broad spectral range, which thus provides a basis for the design rules that are essential for the progress towards effective anti-reflector fabrication. At normal incidence, the hierarchical surfaces achieve reflectances that are 10–80 times lower than that of conventional single-etch nano-microstructures. Portions of the absorbed, transmitted, scattered, and reflected light in the visible-IR spectrum are presented to illustrate the results.

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Section: B Characterizationmentioning

confidence: 99%

Anti-reflective surfaces: Cascading nano/microstructuring

Nishijima¹,

Komatsu²,

Ota³

et al. 2016

APL Photonics

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“…The fabrication of the Au nano-brick arrays was carried out by a standard sequence of electronbeam lithography (EBL), Au deposition, and lift-off as previously reported [16,26]. In short, EBL resist ZEP520A from Zeon was deposited on a glass substrate by spin-coating (3000 rpm for 60 s).…”

Section: Fabrication Of Nano-bricksmentioning

confidence: 99%

Randomization of gold nano-brick arrays: a tool for SERS enhancement

et al. 2013

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Surface enhanced Raman scattering (SERS) was measured on periodic and randomly arranged patterns of Au nano-bricks (rectangular parallelepipeds). Resonant SERS conditions were investigated of a near-IR dye deposited on nanoparticles. Random mixtures of Au nano-bricks with different aspect ratio R showed stronger SERS enhancement as compared to periodic patterns with constant aspect ratio (R varies from 1 to 4). SERS mapping revealed up to ∼ 4 times signal increase at the hot-spots. Experimental observation is verified by numerical modeling and is qualitatively consistent with generic scaling arguments of interaction between plasmonic nanoparticles. The effect of randomization on the polarization selectivity for the transverse and longitudinal modes of nano-bricks is shown. , 1998). 33. For example, consider a one-dimensional intensity distribution I 1 (x), having constant value 1 for 0 < x < 10, and a second distribution I 2 (x) having value 0.8 for 0 < x < 8 and 1.8 for 8 < x < 10. While the two distributions have the same average I 1 = I 2 = 1, I 2 (x) is clearly less uniform than I 1 (x). This is reflected in the greater value of the variance estimator I 2 2 / I 2 2 =1.16 with respect to I 2 1 / I 1 2 =1. In order to maximize its value the distribution should have a high degree of non-uniformity, which can be slightly increased by mixing nano-bricks with high aspect ratio, while it is the greatest (thus high enhancement) for a random distribution. When R is increased, for the T-mode the non-uniformity is increased and the wavelength decreased, both of which favor an increase in Raman scattering relative to extinction (as the Raman scattering cross-section is proportional to 1/λ 4 ). For the L-mode, both non-uniformity and wavelength increase, thus the two factors compensate each other, reducing the growth of Raman intensity with R. 34. G. Sun, J. B. Khurgin, and A. Bratkovsky, "Coupled-mode theory of field enhancement in complex metal nanostructures," Phys. Rev. B 84, 045415 (2011).

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“…The primary way of controlling the properties of metals is through creation of alloys. Permittivity control by co-sputtering of Ag and Au has been demonstrated to provide a possibility to engineer the optical response of an binary alloy [17][18][19] and wasrecently extended to ternary Au, Ag and Cu alloys [20]. Solid solutions of Rh and Ag mixed at the atomic level can store hydrogen much like Pd, a functionality non-existent either in pure Rh or Ag [21].…”

Section: Introductionmentioning

confidence: 99%

Optical readout of hydrogen storage in films of Au and Pd

et al. 2017

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For hydrogen sensor and storage applications, films of Au and Pd were (i) cosputtered at different rates or (ii) deposited in a sequential layer-by-layer fashion on a cover glass. Peculiarities of hydrogen uptake and release were optically monitored using 1.3 µm wavelength light. Increase of optical transmission was observed for hydrogenated Pd-rich films of 10-30 nm thickness. Up to a three times slower hydrogen release took place as compared with the hydrogen uptake. Compositional ratio of Au:Pd and thermal treatment of films provided control over the optical extinction changes and hydrogen uptake/release time constants. Higher uptake and release rates were observed in the annealed Au:Pd films as compared to those deposited at room temperature and were faster for the Au-richer films. Three main parameters relevant for sensors: sensitivity, selectivity, stability (reproducibility) are discussed together with the hydrogenation mechanism in Au:Pd alloys.

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Unusual optical properties of the Au/Ag alloy at the matching mole fraction

Cited by 68 publications

References 34 publications

Anti-reflective surfaces: Cascading nano/microstructuring

Anti-reflective surfaces: Cascading nano/microstructuring

Randomization of gold nano-brick arrays: a tool for SERS enhancement

Optical readout of hydrogen storage in films of Au and Pd

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