Optical Properties of Submillimeter Silver Nanowires Synthesized Using the Hydrothermal Method (original) (raw)
Related papers
Preparation and optical properties of silver nanowires and silver-nanowire thin films
Journal of Colloid and Interface Science, 2011
Silver nanowires and silver-nanowire thin films have attracted much attention due to their extensive applications in Surface-Enhanced Raman Scattering (SERS) and Surface-Enhanced Fluorescence (SEF). Thin films of silver nanowires within polyelectrolyte layers of poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) were fabricated by the Spin-Assisted Layer-by-Layer (SA-LbL) method. The surface coverage, thickness, and absorbance properties of the silver-nanowire films were controlled by the number of layers deposited. Both transverse and longitudinal surface plasmon (SP) modes of the silver-nanowires were observed in the absorbance spectra, as was evidence for nanowire interaction. Two-dimensional finite difference time-domain (2D FDTD) simulations predict that the maximum field enhancement occurs at the ends and cross-sectional edges of the wires for the longitudinal and transverse modes, respectively. Silver nanowires were synthesized by a facile, high-yield solvothermal approach, which can be easily manipulated to control the aspect ratio of the nanowires. The effects of polyvinylpyrrolidone (PVP) concentration and molecular weight on the growth of the silver nanowires, which are not documented in the original procedure, are discussed. It is shown that the growth mechanism for silver nanowires in the solvothermal synthesis is similar to that reported for the polyol synthesis.
Optical Properties of Silver Nanowires Conjugated with Protein
Communications in Physics
Optical properties of protein-conjugated metallic nanowires are theoretically investigated based on the Mie theory and the core-shell model. Our numerical calculations show that optical spectra of protein-conjugated nanowires can have more a maximum compared to these nanowires without biomolecules. This finding is in a good agreement with previous experiments. We provide better interpretation for the origin of optical peaks in absorption spectrum of nanowires. Our results can be used for designing biosensors and bio-detectors.
Journal of Alloys and Compounds, 2009
We present a solution chemistry route for the synthesis of silver nanowires and nanoplates done by a facile aqueous solution process using DMF as reducing agent in the presence of PVP without the addition of seed particles. The products were characterized by UV-vis and transmission electron microscopy (TEM). Experimental results indicated that as the reaction is left to stand at room temperature more silver nanowires are developed in solution. However, when the solution is refluxed, it gives rise to stable silver nanoplates. The prepared nanostructures displayed very strong absorption bands at room temperature.
Coloring fluorescence emission with silver nanowires
Applied Physics Letters, 2010
We demonstrate that emission from Rhodamine-6G fluorophores adsorbed on silver nanowires experiences a spectral redshift upon propagation to the distal ends of the nanowire, with the shift being proportional to the propagation distance. The end of a nanowire thus constitutes a tunable fluorescence source controlled by a single easily adjustable parameter, i.e., the position of the excitation focal spot. The effect is made possible by a combination of radiatively undamped plasmon propagation and dispersive ohmic losses in the silver nanowire. The results may be important for the development of plasmonic waveguides, fast fluorescent color switches and various nanoscale fluorescence sensors.
Plasmonic photoluminescence enhancement by silver nanowires
Physica Scripta
Strong enhancement of photoluminescence is demonstrated for CdS nanocrystals and rutheniumbased dye (N719) due to localized surface plasmon resonance of silver nanowires placed on silver film. Alternative reasons for photoluminescence modulation such as mirror effect and uneven coating by dye or nanocrystals due to geometrical factors are discussed. An artifact such as carbon contamination at the surface of silver nanowires at high laser power is demonstrated and taken into consideration. Silver nanowire on silver film is proved to be an effective system for photoluminescence enhancement by localized surface plasmon resonance.
Functionalised Silver Nanowire Structures
Journal of Physics: Conference Series, 2007
Crystalline silver nanowires 60-100 nm in diameter and tens of micrometres in length have been fabricated using a low temperature, solution synthesis technique. We explore the potential of this method to produce functional nanowire structures using two different strategies to attach active molecules to the nanowires: adsorption and displacement. Initially, as-produced silver nanowires capped with a uniaxial-growth-inducing polymer layer were functionalised by solution adsorption of a semiconducting conjugated polymer to generate fluorescent nanowire structures. The influence of nanowire surface chemistry was investigated by displacing the capping polymer with an alkanethiol self-assembled monolayer, followed by solution adsorption functionalisation. The success of molecular attachment was monitored by electron microscopy, absorption and fluorescence spectroscopy and confocal fluorescence microscopy. We examined how the optical properties of such adsorbed molecules are affected by the metallic nanowires, and observed transfer of excitation energy between dye molecules mediated by surface plasmons propagating on the nanowires. Non-contact dynamic force microscopy measurements were used to map the work-function of individual wires, revealing inhomogeneity of the polymer surface coverage.
The Journal of Physical Chemistry C, 2015
High enhancement of fluorescence emission, improved fluorophore photostability, and significant reduction of fluorescence lifetimes have been obtained from high aspect ratio (>100) silver (Ag) nanowires. These quantities are found to depend on the surface loading of Ag nanowires on glass slides, where the enhancement of fluorescence emission increases with the density of nanowires. The surface loading dependence was attributed to the creation of intense electric fields around the network of Ag nanowires and to the coupling of fluorophore excited states that takes place efficiently at a distance of 10 nm from the surface of nanowires, which was confirmed by theoretical calculations. The enhancement of fluorescence emission of fluorescein isothiocyanate (FITC) was assessed by fluorescence spectroscopy and fluorescence-lifetime imaging microscopy (FLIM) to demonstrate the potential of high aspect ratio Ag nanowires. Fluorescence enhancement factors exceeding 14 were observed on Ag nanowires with high loading by FLIM. The photostability of FITC was the highest on nanowires with medium loading under continuous laser excitation for 10 min because of the significant reduction in the fluorescence lifetime of FITC on these surfaces. These results clearly demonstrate the potential of Ag nanowires in metalenhanced fluorescence-based applications of biosensing on planar surfaces and cellular imaging. G . Fluorescence lifetime image and histogram for FITC-labeled avidin on (A) blank glass slides and Ag nanowire-deposited glass slides with (B) low loading, (C) medium loading, and (D) high loading (τ, average lifetime).
Fluorescence Amplification by Electrochemically Deposited Silver Nanowires with Fractal Architecture
Electrochemically deposited silver structures with nanowires 50-100 nm in diameter show high fluorescence amplification and strongly reduced fluorescence lifetimes. Both quantities depend on the structure thickness. With increasing thickness the fluorescence amplification proportionally increases and the fluorescence lifetime decreases. This thickness dependence is caused by fluorophore interaction with a system of plasmon excitations in coupled nanowires extending over micrometer size regions. Thus the amplification is attributed to a combination of extended structure area and strong plasmonic coupling between nanowires which also help to radiatively scatter the fluorescence emission.
Correlating Plasmon Polariton Propagation and Fluorescence Enhancement in Single Silver Nanowires
The Journal of Physical Chemistry C, 2020
We observe correlation between the length of surface plasmon polariton propagation in silver nanowires and the enhancement of fluorescence intensity due to coupling with localized plasmon resonances. The results of excitation wavelength-dependent fluorescence imaging of CdTe QDs uniformly deposited over silver nanowires indicate the strongest enhancement of fluorescence intensity for wavelengths close to the maximum of localized plasmon resonance, with modest reduction of this effect when the excitation shifts toward longer wavelengths. In contrast, when one of the ends of a silver nanowire is excited with a focused laser, we find a reverse relation for surface plasmon polariton propagation. In fact, the energy propagates most efficiently for the longest excitation wavelength of 635 nm. This inverse correlation points toward an apparent trade-off between electric field confinement and plasmon propagation distance in silver nanowires, introducing thus a limit for efficient remote fluorescence detection when fluorescence enhancement is also desired.
Developing a Simple, Effective, and Quick Process to Make Silver Nanowires with a High Aspect Ratio
Materials
A growing number of people are interested in using silver nanowires (AgNWs) as potential transparent and conductive materials. The production of high-performance and high-throughput AgNWs was successfully optimized in this work using a one-step, straightforward, and reproducible modified polyol approach. The factors influencing the morphology of the silver nanowires have undergone extensive research in order to determine the best-optimized approach for producing AgNWs. The best AgNW morphology, with a length of more than 50 m and a diameter of less than 35 nm (aspect ratio is higher than 1700), was discovered to be produced by a mixture of 44 mM AgNO3, 134 mM polyvinylpyrrolidone (PVP) (Mo.Wt 40,000), and 2.4 mM KCl at 160 °C with a stirring rate of 100 rpm. With our improved approach, the overall reaction time was cut from almost an hour with the conventional polyol method to a few minutes. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and ultraviolet (UV) spectrosco...