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Au Film (au + film)

Distribution by Scientific Domains

Polymers and Materials Science	50%
Physics and Astronomy	50%

Selected Abstracts

Induced SER-Activity in Nanostructured Ag,Silica,Au Supports via Long-Range Plasmon Coupling

ADVANCED FUNCTIONAL MATERIALS, Issue 12 2010
Jiu-Ju Feng
Abstract A novel Ag,silica,Au hybrid device is developed that displays a long-range plasmon transfer of Ag to Au leading to enhanced Raman scattering of molecules largely separated from the optically excited Ag surface. A nanoscopically rough Ag surface is coated by a silica spacer of variable thickness from ,1 to 21,nm and a thin Au film of ,25,nm thickness. The outer Au surface is further functionalized by a self-assembled monolayer (SAM) for electrostatic binding of the heme protein cytochrome c (Cyt c) that serves as a Raman probe and model enzyme. High-quality surface-enhanced resonance Raman (SERR) spectra are obtained with 413,nm excitation, demonstrating that the enhancement results exclusively from excitation of Ag surface plasmons. The enhancement factor is estimated to be 2,×,104,8,×,103 for a separation of Cyt c from the Ag surface by 28,47,nm, corresponding to an attenuation of the enhancement by a factor of only 2,6 compared to Cyt c adsorbed directly on a SAM-coated Ag electrode. Upon immobilization of Cyt c on the functionalized Ag,silica,Au device, the native structure and redox properties are preserved as demonstrated by time- and potential-dependent SERR spectroscopy. [source]

Fabrication of dendrite-like Au nanostructures and their enhanced photoluminescence emission

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2007
Ying Hu
Abstract Special hierarchical dendrite-like Au (DLAu) nanostructures were fabricated facilely between the gaps of Au electrodes by an electrochemical method. The composition, morphology and crystallinity of the DLAu nanostructures were characterized using energy dispersive spectroscopy, field emission scanning electron microscopy and X-ray diffraction, respectively. The formation of these nanostructures is attributed to the distribution of the local electrical field between the Au electrodes and a diffusion-limited aggregation process. Photoluminescence (PL) having an emission peak near 530 nm is observed from these nanostructures, which is attributed to the recombination of the s,p band electrons near the Fermi energy with the d band holes in the DLAu nanostructures generated by optical excitation. We believe that such PL enhancement compared to a smooth Au film is due to the local-field enhancement from the surface plasmon resonance of the DLAu nanostructures. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Gold Coating of Poly(ethylene terephthalate) Modified by Argon Plasma

PLASMA PROCESSES AND POLYMERS, Issue 1 2007
Vladimír Kotál
Abstract Little information has been published concerning the interaction of gold with polymers. In the context of this lack of information, we decided to investigate the effect of Ar plasma treatment on the surface properties of poly(ethylene terephthalate) (PET) in order to examine its possible application for metal-polymer adhesion improvement. The plasma treatment leads to an immediate increase of the PET's surface wettability, which however significantly depends on the sample aging, more specifically on the time elapsed after the treatment. X-ray photoelectron spectroscopy (XPS) measurements revealed that the oxygen concentration in the surface-near layers increases as a result of the treatment, but that it also changes with time for the samples in contact with the atmosphere, probably as a result of polar group rearrangements. Plasma initiated ablation and Au sputtering increases the surface roughness. The nanoindenter measurements revealed that the treatment increases the microhardness of treated PET. Contrary to hardness, the elastic modulus decreases. Scratch tests showed that the deformation of samples consisting of Au coatings deposited on both pristine and treated PET was elastic rather than plastic. We conclude from the nanoindenter data that the plasma modification does not affect the adhesion of gold on PET, but the X-ray diffractometry (XRD) analysis showed that the Au film deposited on the as-treated PET, and on PET aged for 14 d are the most stable. [source]

Second harmonic generation spectroscopy on Si surfaces and interfaces

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 8 2010
Kjeld Pedersen
Abstract Optical second harmonic generation (SHG) spectroscopy studies of Si(111) surfaces and interfaces are reviewed for two types of systems: (1) clean 7,×,7 and -Ag reconstructed surfaces prepared under ultra-high vacuum conditions where surface states are excited and (2) interfaces in silicon-on-insulator (SOI) structures and thin metal films on Si surfaces where several interfaces contribute to the SHG. In all the systems resonances are seen at interband transitions near the bulk critical points E1 and E2. On the clean surfaces a number of resonances appear below the onset of bulk-like interband transitions that can be referred to excitations of dangling bond surface states. Adsorption of oxygen leads to formation of a new surface resonance. Such resonances appearing in the region between the bulk critical points E1 and E2 are also shown to be important for Si/oxide interfaces in SOI structures. Finally, examples of spectroscopy on layers buried below thin Ag and Au films are given. [source]

Cu underpotential deposition on Au controlled by in situ Spectroscopic Ellipsometry

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2008
Mirko Prato
Abstract We have studied Cu electrodeposition on well defined Au films using real time Spectroscopic Ellipsometry (SE). SE allows to discriminate the under-potential (UP) and over-potential (OP) regimes. In the UP regime, tiny yet reproducible variations of , and , parameters indicate the formation of two phases with slightly different optical behavior. The phase at the largest coverage is assigned to a Cu monolayer. The SE response in the OP regime shows a marked dependence on the potential scan rate. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Impact of Annealing on the Conductivity of Amorphous Carbon Films Incorporating Copper and Gold Nanoparticles Deposited by Pulsed Dual Cathodic Arc

PLASMA PROCESSES AND POLYMERS, Issue S1 2009
Jose Luis Endrino
Abstract The influence of annealing in argon at 300,°C on the conductivity, phase stability and electronic structure of hydrogen-free amorphous carbon (a-C) films containing copper (a-C:Cu) and gold (a-C:Au) nanoclusters was investigated. The motivation of this work is twofold: (1) to study the thermal stability of a-C:Cu and a-C:Au films and (2) to point out the relevance of X-ray absorption near edge structure (XANES) technique to study the structural evolution of metal-doped a-C nanocomposites. The films were produced at room temperature using a selective-bias pulsed dual-cathode arc deposition technique. Compositional analysis was performed with secondary neutral mass spectroscopy whereas grazing incidence X-ray diffraction (GIXRD) was used to monitor phase transformation and identify the dispersion or agglomeration of the crystallites within the carbon matrix. XANES spectra at the C-K was used to investigate the effect of annealing in argon on the electronic structure of the a-C matrix, while Cu K and Au L-edges were investigated on a-C:Cu and a-C:Au samples, respectively, to study the nanocluster evolution. XANES showed that the a-C host matrix increased its graphitic character and that stress was relieved upon annealing. No relevant changes were observed in the Au arrangements in a-C:Au films. In the case of the a-C:Cu samples, the Cu-K XANES spectra indicated the formation of Cu2O crystals which correlated well with GIXRD spectra and the decrease in conductivity. [source]