Tunability of the Refractive Index of Gold Nanoparticle Dispersions

Kubo, Shoichi; Díaz, Arturo Pulido; Tang, Ying; Mayer, Theresa S.; Khoo, Iam Choon

doi:10.1021/nl071893x

Cited by 147 publications

(110 citation statements)

References 32 publications

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“…m ε and LC ε are the dielectric constants of the metal gold and LC medium respectively. The value of 2 m ε  [29]. It does not change much in the visible range of light, so it has been kept constant, and LC ε varies from 2.1774 to 2.4292 in the surrounding of GNP at optical frequencies of incident light.…”

Section: Experiments and Analysismentioning

confidence: 99%

Anisotropic shift of surface plasmon resonance of gold nanoparticles doped in nematic liquid crystal

Choudhary¹,

Li²

2014

Opt. Express

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Study of the liquid crystal (LC) director around nanoparticles has been an important topic of research very recently, since it allows design and fabrication of next-generation LC devices that are impossible in the past. In our experiment, alkanethiol-capped gold nanoparticles (GNPs) were dispersed in nematic LC. Analysis of the LC director around GNPs was performed by investigating the behavior of surface plasmon polariton (SPP) absorption peaks of the GNPs using spectrophotometry technique. It is found that the incident linearly polarized light orientated at 0°, 45°, and 90° angles with respect to the rubbing direction experiences varying interaction with the LC medium. The corresponding transmission of light reveals the anisotropic shift in wavelength of SPP peak. The anisotropic behavior of SPPs of the GNPs is in agreement with theoretical calculations. Science 275(5307), 1770-1773 (1997). 8. R. Yamamoto, "Simulating particle dispersions in nematic liquid-crystal solvents," Phys. Rev. Lett. 87(7), 075502 (2001). 9. J. Fukuda, M. Yoneya, and H. Yokoyama, "Nematic liquid crystal around a spherical particle: Investigation of the defect structure and its stability using adaptive mesh refinement," Eur Phys J E Soft Matter 13(1), 87-98 (2004). 10. M. A. Bates, "Nanospheres in a nematic liquid crystal solvent: the influence of particle size," Liq. Cryst. 32(11-12), 1525-1529 (2005 ©2014 Optical Society of America

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Section: Experiments and Analysismentioning

confidence: 99%

Anisotropic shift of surface plasmon resonance of gold nanoparticles doped in nematic liquid crystal

Choudhary¹,

Li²

2014

Opt. Express

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“…Microfluidic devices were prepared by soft lithography from masters prepared by photolithography (31). Simulation of the optical properties was performed as a 1D transfer matrix method implemented in Matlab and effects of gold nanoparticles were included by adjusting the refractive index profile (43). Optical spectra of individual photonic balls were measured through a microscope objective lens.…”

Section: Methodsmentioning

confidence: 99%

Color from hierarchy: Diverse optical properties of micron-sized spherical colloidal assemblies

Vogel

Utech

England

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

275

351

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Materials in nature are characterized by structural order over multiple length scales have evolved for maximum performance and multifunctionality, and are often produced by self-assembly processes. A striking example of this design principle is structural coloration, where interference, diffraction, and absorption effects result in vivid colors. Mimicking this emergence of complex effects from simple building blocks is a key challenge for manmade materials. Here, we show that a simple confined selfassembly process leads to a complex hierarchical geometry that displays a variety of optical effects. Colloidal crystallization in an emulsion droplet creates micron-sized superstructures, termed photonic balls. The curvature imposed by the emulsion droplet leads to frustrated crystallization. We observe spherical colloidal crystals with ordered, crystalline layers and a disordered core. This geometry produces multiple optical effects. The ordered layers give rise to structural color from Bragg diffraction with limited angular dependence and unusual transmission due to the curved nature of the individual crystals. The disordered core contributes nonresonant scattering that induces a macroscopically whitish appearance, which we mitigate by incorporating absorbing gold nanoparticles that suppress scattering and macroscopically purify the color. With increasing size of the constituent colloidal particles, grating diffraction effects dominate, which result from order along the crystal's curved surface and induce a vivid polychromatic appearance. The control of multiple optical effects induced by the hierarchical morphology in photonic balls paves the way to use them as building blocks for complex optical assemblies-potentially as more efficient mimics of structural color as it occurs in nature.self-assembly | colloids | photonic crystal | structural color | hierarchy H ierarchical design principles, i.e., the structuration of material over multiple length scales, are ubiquitously used in nature to maximize functionality from a limited choice of available components. Hierarchically structured materials often provide better performance than their unstructured counterparts and novel properties can arise solely from the multiscale structural arrangement. Examples can be found in the extreme water repellency of the lotus leaf (1); the outstanding mechanical stability and toughness of sea creatures such as sea sponges (2) and abalone shells (3); and the bright coloration found in beetles, birds, and butterflies (4, 5).To achieve the strongest visual effects, many organisms combine optical effects arising from light interacting with structured matter at different length scales (6). Structural periodicity on the scale of visible light wavelengths can result in regular optical density variations that give rise to bright, iridescent colors due to pronounced interference effects (4). At the micron scale, regular structural features act as diffraction gratings that produce vivid, rainbow coloration (7) and are used to control scatteri...

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“…With the boost of nanotechnology in recent decades, gold nanoparticles have been playing an active role in fields of biology 35 , medicine 36 , nanocatalysis 37 and metamaterials [38][39][40] etc. The shape of gold nanoparticles can be well controlled during synthesis 41 .…”

Section: Introductionmentioning

confidence: 99%

“…As one of the least reactive chemical elements, gold is an elite candidate for long-term use, especially in corrosive environments. In recent years, there have been plenty of work on the nanogold photonic crystals and electromagnetic metamaterials, exhibiting interesting phenomena with rich physics such as Fano resonance 40 and tunable refractive index 39 .…”

Section: Introductionmentioning

confidence: 99%

Mechanical wave propagation within nanogold granular crystals

Zheng

2017

Extreme Mechanics Letters

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We computationally investigate the wave propagation characteristics of nanoscopic granular crystals composed of one-dimensionally arrayed gold nanoparticles using molecular dynamics simulation. We examine two basic configurations, i.e. homogeneous lattices and diatomic lattices with mass-mismatch.We discover that homogeneous lattices of gold nanospheres support weakly dissipative and highly localized solitary wave at 300 K, while diatomic lattices have a good tuning ability of transmittance and wave speed. We establish a validated nonlinear spring contact model with the consideration of complex interactions between gold nanospheres which reveals the physical nature of wave behaviors at nanoscale. This work sheds light on the application of nanogold as a novel mechanical wave tuner, qualitatively and fundamentally different from its counterpart granular materials at meso-and macroscale.

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Tunability of the Refractive Index of Gold Nanoparticle Dispersions

Cited by 147 publications

References 32 publications

Anisotropic shift of surface plasmon resonance of gold nanoparticles doped in nematic liquid crystal

Anisotropic shift of surface plasmon resonance of gold nanoparticles doped in nematic liquid crystal

Color from hierarchy: Diverse optical properties of micron-sized spherical colloidal assemblies

Mechanical wave propagation within nanogold granular crystals

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