Preparation of Au@Ag Core-Shell Nanorods and Investigation of its Surface Plasmon

2012 ◽  
Vol 535-537 ◽  
pp. 446-449
Author(s):  
Wei Yuan ◽  
Pei Jie Wang ◽  
Yan Fang
Keyword(s):  
Aspect Ratio ◽  
Surface Plasmon ◽  
Gold Nanorods ◽  
Chemical Reduction ◽  
Silver Ions ◽  
Blue Shift ◽  
Core Shell ◽  
Transverse Modes ◽  
Growth Method ◽  
Length Width

Different aspect ratio (length/width) gold nanorods were prepared in aqueous solution by seeding growth method. Aspect ratio of the nanorods was controlled accurately by changing the silver ions concentration. Ultraviolet-visible (UV-vis) spectra demonstrate the regularation that longitudinal plasmon resonance absorption wavelength of gold nanorods reveal red shift with the increase of aspect ratio. Gold nanorods were wrapped with Ag shells by chemical reduction silver ions on its surface. Different from gold nanorods, the transverse modes of the Au@Ag core-shell nanorods have two bands which contributed from the Ag and Au, respectively. On the other hand, centers of longitudinal surface plasmon of the core-shell nanorods exhibit blue shift with the Ag shell thickness increasing.

Effect of aspect ratio on the chirality of gold nanorods prepared through conventional seed-mediated growth method

2021 ◽  
Vol 1152 ◽  
pp. 338277
Author(s):  
Xiaojuan Zhou ◽  
Qiang Liu ◽  
Xiaoyu Shi ◽  
Chunli Xu ◽  
Baoxin Li
Keyword(s):  
Aspect Ratio ◽  
Gold Nanorods ◽  
Growth Method ◽  
Seed Mediated

scholarly journals Numerical Study on the Surface Plasmon Resonance Tunability of Spherical and Non-Spherical Core-Shell Dimer Nanostructures

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1728
Author(s):  
Joshua Fernandes ◽  
Sangmo Kang
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Surface Plasmon Resonance ◽  
Aspect Ratio ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Shell Thickness ◽  
Numerical Study ◽  
Field Enhancement ◽  
Core Shell

The near-field enhancement and localized surface plasmon resonance (LSPR) on the core-shell noble metal nanostructure surfaces are widely studied for various biomedical applications. However, the study of the optical properties of new plasmonic non-spherical nanostructures is less explored. This numerical study quantifies the optical properties of spherical and non-spherical (prolate and oblate) dimer nanostructures by introducing finite element modelling in COMSOL Multiphysics. The surface plasmon resonance peaks of gold nanostructures should be understood and controlled for use in biological applications such as photothermal therapy and drug delivery. In this study, we find that non-spherical prolate and oblate gold dimers give excellent tunability in a wide range of biological windows. The electromagnetic field enhancement and surface plasmon resonance peak can be tuned by varying the aspect ratio of non-spherical nanostructures, the refractive index of the surrounding medium, shell thickness, and the distance of separation between nanostructures. The absorption spectra exhibit considerably greater dependency on the aspect ratio and refractive index than the shell thickness and separation distance. These results may be essential for applying the spherical and non-spherical nanostructures to various absorption-based applications.

scholarly journals Investigation on the Effect of Centrifugation Speed on the Shape Separation of Gold Nanorods

2018 ◽  
Vol 7 (4.30) ◽  
pp. 330 ◽  
Author(s):  
Caessandra Addine Minun ◽  
Nur Zehan An’Nisa ◽  
Marlia Morsin ◽  
Nur Liyana Razali ◽  
Suratun Nafisah ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Gold Nanorods ◽  
Localized Surface Plasmon Resonance ◽  
Crystal Orientation ◽  
Surface Density ◽  
Morphological Analysis ◽  
Localized Surface Plasmon ◽  
Plasmon Peak ◽  
Sensing Material ◽  
Growth Method

High-quality gold nanorods (AuNRs) with a uniform aspect ratio and sizes are crucial for applications in biomedical or sensor industry. AuNRs is implementing Localized Surface Plasmon Resonance (LSPR) as sensing method which is highly dependent on the size, separation of nanoparticles, aspect ratio and the shape of the nanoparticles. Thus, in this process, the shape, surface density and aspect ratio of AuNRs were investigated to be used further as LSPR sensing material. The AuNRs was prepared using Seed Mediated Growth Method (SMGM) and the growth solution of the AuNRs was centrifuged with the speed ranging from 2500 rpm to 5000 rpm to separate the particles shaper prior to deposition as thin film. The XRD result shows the peak at 2θ = 38º which shows the (111) crystal orientation of the AuNRs. There are also two distinct peaks formed at the absorption spectra graph obtained from the UV-Vis result which associated with transverse plasmon peak (t-LSPR) and longitudinal plasmon peak (l-LSPR). The t-LSPR peak is significantly smaller than the l-LSPR and located in the wavelength ranges from 500 nm to 560 nm whereas the l-LSPR of the AuNRs shows a stronger and a higher peak which is located in the wavelength ranges from 700 nm to 780 nm. The morphological analysis using FESEM shows that the higher centrifugation speed separates the AuNRs with higher aspect ratio and higher surface density.

Extraordinary Surface Plasmon Coupled Emission Using Core/Shell Gold Nanorods

2012 ◽  
Vol 116 (16) ◽  
pp. 9259-9264 ◽  
Author(s):  
Huimin Su ◽  
Yongchun Zhong ◽  
Tian Ming ◽  
Jianfang Wang ◽  
Kam Sing Wong
Keyword(s):  
Surface Plasmon ◽  
Gold Nanorods ◽  
Core Shell

scholarly journals Hydroquinone-Based Fabrication of Gold Nanorods with a High Aspect Ratio and LSPR Greater than 850 nm to Be Used as a Surface Plasmon Resonance Platform for Rapid Detection of Thiophanate Methyl

2020 ◽  
Vol 10 (10) ◽  
pp. 3654
Author(s):  
Hang Nguyen Thi Nhat ◽  
Ngoc Thuy Trang Le ◽  
Nguyen Thi Phuong Phong ◽  
Dai Hai Nguyen ◽  
Minh-Tri Nguyen-Le
Keyword(s):  
Surface Plasmon Resonance ◽  
Aspect Ratio ◽  
Surface Plasmon ◽  
Gold Nanorods ◽  
Plasmon Resonance ◽  
High Aspect Ratio ◽  
Rapid Detection ◽  
Plasmon Resonance Peak ◽  
Thiophanate Methyl ◽  
X Ray

The use of gold nanorods (AuNRs) as surface-enhanced Raman scattering (SERS) substrates has gained much attraction due to their remarkably aspect-ratio-dependent plasmonic properties. In this report, we described the development of AuNRs with a high aspect ratio and longitudinal surface plasmon resonance (LSPR) >850 nm through a hydroquinone-based fabrication with minor modifications. The synthesis started with the reduction of chloroauric acid (HAuCl4) by sodium borohydride (NaBH4) to make gold nanoseeds from which AuNRs were grown with the aid of silver nitrate (AgNO3), HAuCl4, cetyltrimethylammonium bromide (CTAB), and hydroquinone (HQ). Scanning electron microscopy coupled with energy-dispersive X-ray (SEM-EDX), Transmission electron microscope (TEM), X-ray diffraction (XRD) and Ultra-violet-Visible spectroscopy (UV-Vis) were performed to study the shape, size, and structural and optical properties of AuNRs, respectively. The results showed that AuNRs with high aspect ratios (AR > 3) were single crystals with a heterogenous size distribution, and that the growth of Au nanoseeds into AuNRs took place along the [001] direction. AuNRs exhibited two plasmon resonance peaks at 520 nm and 903 nm, while gold nanoseeds had only a plasmon resonance peak at 521 nm. The as-synthesized AuNRs also showed SERS effects for thiophanate methyl, a broad-spectrum fungicide, with the limit of detection down to 5 mg/L of the fungicide. AuNR-coated glass can serve as a SERS-based sensing platform for rapid detection of thiophanate methyl with high sensitivity and reproducibility.

Unstable Reshaping of Gold Nanorods Prepared by a Wet Chemical Method in the Presence of Silver Nitrate

2006 ◽  
Vol 6 (11) ◽  
pp. 3355-3359 ◽  
Author(s):  
Muhammad Iqbal ◽  
Giyoong Tae
Keyword(s):  
Silver Nitrate ◽  
Gold Nanorods ◽  
Small Diameter ◽  
Silver Ions ◽  
Blue Shift ◽  
Aqueous Environment ◽  
Ctab Concentration ◽  
Seed Particles ◽  
The Stability ◽  
Growth Approach

We characterized the stability of the gold nanorods synthesized by means of a seed mediated growth approach in the presence of AgNO3, which consists of synthesis of small diameter seed particles (∼4 nm) and subsequent growth of these nanoparticles into nanorods by addition to gold salt solution containing cetyltrimethylammonium bromide (CTAB) in the presence of ascorbic acid. The presence of silver nitrate significantly enhanced the nanorod synthesis as previously reported. However, the synthesized nanorods were unstable and reshaped in aqueous environment; the continuous blue-shift of the 2nd plasmon bands was monitored and the changes in the nanorod morphologies were also observed by electron microscopy with increasing storage time. This reshaping was observed at wide CTAB concentration range regardless of the removal of the unreacted gold or silver ions.

scholarly journals Investigation of thermal conductivity property of plasmonic nanofluids based on gold nanorods prepared by seed-mediated growth method

2019 ◽  
Vol 2 (22) ◽  
pp. 119-133
Author(s):  
Mahsa Mohammadzadeh ◽  
Mohsen Ashjari ◽  
Davoud Zare
Keyword(s):  
Thermal Conductivity ◽  
Aspect Ratio ◽  
Gold Nanorods ◽  
Thermal Conductivity Coefficient ◽  
Volume Fraction ◽  
Effect Of Temperature ◽  
Basic Fluid ◽  
Vis Spectroscopy ◽  
Growth Method ◽  
Seed Mediated

In this paper, nanofluids were prepared based on gold nanorods in basic fluid, water, by single-stage chemical reduction and in different volume fractions and the used gold nanorods were synthesized by seed-mediated growth method in different dimensional ratios. The properties of the prepared nanoparticles, including crystalline size, aspect ratio, surface properties, nanoparticle purity, shape and morphology of nanostructures were investigated using x-ray diffraction, UV-vis spectroscopy, FT-IR, and transmitted electron microscopy. The effect of changing parameters of Nano rod dimensions, changes in Nano rod volume fraction in water and also the effect of temperature on the nanofluid thermal conductivity coefficient were investigated using transient hot wire method. The results showed that reducing the aspect ratio, increasing the volume fraction and increasing the temperature increase the thermal conductivity. In fact, results show that an increase in the nanorods aspect ratio with a constant volume fraction of 1:50 of gold in water nanorod and at room temperature leads to a decrease in the thermal conductivity of the nanofluid. Also, increasing the two parameters of volume fraction and temperature significantly increases the thermal conductivity coefficient.

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