Convenient synthesis of silver nanoplates with adjustable size through seed mediated growth approach

Silver nanoplates,with average thickness about 5 nm and average tunable size from 40 to 500 nm,were synthesized via a simple room-temperature solution-phase chemical reduction method in the presence of appropriate concentration of trisodium citrate and silver seeds.The optical in-plane dipole plasmon resonance bands of these silver plates could be tuned from 520 to 1100 nm.Control experiments were explored for understanding of the growth mechanism.It is found that both the amount of citrate ions and the small silver seeds added to the growth solution are the key to controlling the silver nanoplates without changing their thickness and crystal structure.Small silver seeds are found to play an important role in the formation of large thin silver nanoplates when poly（vinylpyrrolidone）（PVP） are used as capping agent.

将引发新一轮材料革命的光学异构体

分辨气味 日本NTT生活环境研究所日前宣布,成功开发了一种利用纳米技术来区分存在于"左手"和"右手"之间关系的光学异构体的新方法.该方法利用了在生物科技领域中用干测定抗原-抗体反应的表面等离子体共振(Surface Plasmon Resonance,SPR)法.

Performance Evaluation of a Bilayer SPR-Based Fiber Optic RI Sensor With TiO2 Using FDTD Solutions

We proposed a new bilayer surface plasmon resonance-based fiber-optic refractive index sensor with silver and an over-layer of TiO2. We numerically investigated the optimal thickness of TiO2 over-layer in the proposed sensor and compared its performance to that based on typical bimetallic layers of silver-and-gold in the aqueous media using finite-difference time domain approach. We show that the use of TiO2 over-layer greatly improves the sensor performance in terms of sensitivity and signal-to-noise ratio compared to that with gold as the over-layer. Not only does the TiO2 over-layer offer a cost-effective alternative to gold for overcoming the oxidation problem, but also it allows resonance wavelength-tunability.

Fluorescence enhancement of Tb^(3+) complexes by adding silica-coated silver nanoparticles

Six kinds of terbium ternary complexes with halo-benzoic acids were synthesized. Their compositions were determined by C, H elemental analyzer and EDTA titration. The infrared spectra, ultraviolet absorption spectra, and fluorescence spectra were also measured to identify the complexes. Elemental analysis showed that the compositions of these complexes were Tb（p-BrBA）3- H20, Tb（p-CIBA）3- 2H20, Tb（p-FBA）3- H20, Tb（o-FBA）3·2H20, Tb（o-CIBA）3· H20, and Tb（o-BrBA）3. H20, respectively. The monodispersed Ag@SiO2 core-shell nanoparticles with silica thicknesses of 10, 15, and 25 nm were success- fully prepared and characterized by transmission-electron microscopy. Fluorescence intensities of the complexes were detected before and after Ag@SiO2core-shell nanoparticles were added; the enhancement times were related to the silica-shell thick- ness. The fluorescence enhancement times were largest when the thickness of the silica shell was 25 nm. The mechanism may be attributed to the localized surface-plasmon resonance. Furthermore, the enhancement effect of terbium fluoro-benzoate complexes was the strongest in these complexes. This result may be attributed to the hydrogen bond between the hydroxyl on the surface of the silica shell and the fluorine atom.

Enhancement of adjustable localized surface plasmon resonance in ZnO nanocrystals via a dual doping approach

Recently, the localized surface plasmon resonance （LSPR） concept was expanded from noble metals to doped semiconductor nanocrystals （NCs）. However, the strengthening of the intrinsically very weak LSPR in NCs remains a great challenge for its applications in optics, electronics and optoelectronics fields. In this work, we report on the remarkable strengthening and controllability of LSPR in ZnO through a dual-doping strategy. First, high quality In-doped ZnO （IZO） NCs with intense LSPR were synthesized by a simple single-pot method. Importantly, the LSPR can be tuned by simply adjusting the concentration of In dopant, as well as by UV light irradiation （photo-induced doping）. The pattern of electricity of an IZO NC film matches the shift of LSPR independent of dopant concentration. The UV light irradiation clearly enhanced the electrical properties of the films （350 fl/sq） due to increase carrier density explained by LSPR and confirmed by X-ray photoelectron spectroscopy, The IZO NCs can be easily dispersed in various organic solvents and serve as inks for assembling uniform films via solution processes. These IZO NC ink is promising for application in next-generation solution-based field effect transistors and other optoelec- tronic devices.