Experimental identification of the out-of-plane phonon mode of a few layered graphene from individual Au nanoparticle-Au film junctions

2013 ◽  
Vol 103 (7) ◽  
pp. 071903 ◽  
Author(s):  
Won-Hwa Park ◽  
Myunghee Jung ◽  
Jin-San Moon ◽  
Seok Hwan Noh ◽  
Tae Hyeong Kim ◽  
...  
2007 ◽  
Vol 342-343 ◽  
pp. 865-868 ◽  
Author(s):  
Kang Deuk Seo ◽  
Seong Dae Oh ◽  
Seong Ho Choi ◽  
Sang Hyub Oh ◽  
Jin Chun Woo ◽  
...  

In order to prepare the enzyme electrode for sensing of chemical molecules, the Au was coated on the surface of PP film by sputter coater. Polyaniline (PANI) was polymerized on the surface of the coated Au film by electrochemical polymerization of aniline in order to use working electrode. Subsequently, horseradish peroxide (HRP) was immobilized on PANI electrode as follows: Method I. The HRP was immobilized on the surface of PANI electrode by using Au nanoparticle as linker (physical adsorption). Method II. The HRP was immobilized on the surface of PANI electrode by using 2-aminothiophenol and Au nanoparticle as linker (Self-assembling immobilization). Method III. HRP was directly immobilized with PANI electrode by using glutaric dialdehyde as linker (covalent bonding). The sensing efficiency of the prepared HRP-PANI electrode was also examined. The sensing efficiency of the HRP-PANI electrode for H2O2 was as following order; Method I > Method III > Method II..


2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Wei Qi ◽  
Weigen Chen ◽  
Fu Wan ◽  
Jingxin Zou ◽  
Zhaoliang Gu

Furfural is an important chemical solvent and intermediate. Sensitive detection of this compound has attracted great interest in various fields. Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive method for material detection because of its optical enhancement effect of plasmonic nanostructures. This study presents a simple and versatile method to synthesize a SERS substrate, where polyaminothiophenol (PATP) was used to realize the stable combination of Au nanoparticles (AuNPs) and Au film via self-assembly. The near-field electric field distribution was calculated using the finite difference time domain (FDTD) simulation to determine the parameters responsible for electric field enhancement. The simulation results show that SERS enhanced factors are sensitive to interparticle spacing and materials for solid support but insensitive to particle size. Moreover, the experimental results show that the optimized substrates with the highest Raman activity were formed by six layers of 60 nm AuNPs decorated on a 30 nm thick Au film, thereby validating the simulation results. The SERS factor of the optimal substrates is approximately 5.57 × 103, and thein situdetection limit is 4.8 ppm. The 3D Raman spectra, relative standard deviation values for major peaks, and changes in signal intensity with time show the good reproducibility and stability of the substrates.


2011 ◽  
Vol 2 ◽  
pp. 318-326 ◽  
Author(s):  
Dong Wang ◽  
Ran Ji ◽  
Peter Schaaf

The fabrication of precise 2D Au nanoparticle arrays over a large area is presented. The technique was based on pre-patterning of the substrate before the deposition of a thin Au film, and the creation of periodic particle arrays by subsequent dewetting induced by annealing. Two types of pre-patterned substrates were used: The first comprised an array of pyramidal pits and the second an array of circular holes. For the dewetting of Au films on the pyramidal pit substrate, the structural curvature-driven diffusion cooperates with capillarity-driven diffusion, resulting in the formation of precise 2D particle arrays for films within a structure dependent thickness-window. For the dewetting of Au films on the circular hole substrate, the periodic discontinuities in the films, induced by the deposition, can limit the diffusion paths and lead to the formation of one particle per individual separated region (holes or mesas between holes), and thus, result in the evolution of precise 2D particle arrays. The influence of the pre-patterned structures and the film thickness is analyzed and discussed. For both types of pre-patterned substrate, the Au film thickness had to be adjusted in a certain thickness-window in order to achieve the precise 2D particle arrays.


2018 ◽  
Vol 32 (15) ◽  
pp. 1850192 ◽  
Author(s):  
Junhuai Xiang ◽  
Chu Wang ◽  
Huilin Li ◽  
Dandan Men ◽  
Xiaofang Qiu ◽  
...  

Periodic hexagonal gold crystal spherical nanoparticle arrays with controllable size and periodicity are fabricated by physical vapor deposition and further heat treatment based on monolayer colloidal crystal template. The size and center-to-center spacing of nanoparticles (NPs) were manipulated conveniently by tuning the deposition thickness of Au film and the size of colloidal spheres of the template, respectively. The thickness range of deposited Au film dependent on the size of colloidal spheres was investigated comprehensively. Dewetting model was established and employed to analyze the whole process of the evolution from gold film to spherical nanoparticle with uniform size. Additionally, localized surface plasmon resonance (LSPR) responses of these Au nanoparticle arrays were systematically measured. It is found that the extinction properties are significantly influenced by the particle size and periodicity of arrays. With the increase of particle size, the LSPR peak shows a red shift due to the quantum size effect of the nanoscaled Au particle. Meanwhile, the diffraction peaks also show small red shift due to a slight increase of average refractive index of arrays. This is highly helpful to improve its practical applications for detecting biochemical molecules based on LSPR and diffraction peak sensing.


Author(s):  
Rakesh Murthy ◽  
Dan O. Popa

A MEMS (Micro Electro Mechanical Systems) based four degree of freedom articulated microrobot is presented as an example of next generation miniaturized top down manipulators. The robot occupies 6mm3 in total volume with room for further down scaling. The operating work volume is 50μm × 50μm × 75μm with a 2P2R (Prismatic Prismatic Revolute Revolute) kinematic configuration — X, Y, Pitch and Yaw. The presented microrobot design rises above commonly encountered performance tradeoff’s of previous MEMS positioners such as range of motion vs. exerted force and range of motion vs. precision. It is constructed using a combination of hybrid microassembly and high aspect ratio micromachining. Structurally, the first version of the microrobot consists of Silicon 2 1/2 D parts and a 30μm diameter Cu wire. The robot joints and attachment of the end effector are accomplished by microassembly using compliant snap-fasteners, monolithic flexure joints, and epoxy glue. Actuation is carried out by two banks of in-plane electrothermal actuators, one coupled through an out of plane compliant socket, and the other one coupled remotely using a 30 μm diameter Cu wire. In this paper we present the microrobot kinematic design, and experimental identification of the robot Jacobian. Preliminary experimental characterization of the microrobot shows that it is repeatable to less than 0.5 μm along XY axes and 0.015 degrees along Pitch and Yaw DOFs. Finally, the robot was configured to carry an AFM tip and we demonstrate nano indentation sequences on a Parylene substrate.


2017 ◽  
Author(s):  
Shuang Wang ◽  
Kewu Li ◽  
Rui Zhang ◽  
Ning Jing ◽  
Youhua Chen ◽  
...  

Author(s):  
G.A. Bertero ◽  
R. Sinclair

Pt/Co multilayers displaying perpendicular (out-of-plane) magnetic anisotropy and 100% perpendicular remanent magnetization are strong candidates as magnetic media for the next generation of magneto-optic recording devices. The magnetic coercivity, Hc, and uniaxial anisotropy energy, Ku, are two important materials parameters, among others, in the quest to achieving higher recording densities with acceptable signal to noise ratios (SNR). The relationship between Ku and Hc in these films is not a simple one since features such as grain boundaries, for example, can have a strong influence on Hc but affect Ku only in a secondary manner. In this regard grain boundary separation provides a way to minimize the grain-to-grain magnetic coupling which is known to result in larger coercivities and improved SNR as has been discussed extensively in the literature for conventional longitudinal recording media.We present here results from the deposition of two Pt/Co/Tb multilayers (A and B) which show significant differences in their coercive fields.


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