Two-dimensional ultrathin gold film composed of steadily linked dense nanoparticle with surface plasmon resonance

Background

Noble metallic nanoparticles have prominent optical local-field enhancement and light trapping properties in the visible light region resulting from surface plasmon resonances.

Results

We investigate the optical spectral properties and the surface-enhanced Raman spectroscopy of two-dimensional distinctive continuous ultrathin gold nanofilms. Experimental results show that the one- or two-layer nanofilm obviously increases absorbance in PEDOT:PSS and P3HT:PCBM layers and the gold nanofilm acquires high Raman-enhancing capability.

Conclusions

The fabricated novel structure of the continuous ultrathin gold nanofilms possesses high surface plasmon resonance properties and boasts a high surface-enhanced Raman scattering (SERS) enhancement factor, which can be a robust and cost-efficient SERS substrate. Interestingly, owing to the distinctive morphology and high light transmittance, the peculiar nanofilm can be used in multilayer photovoltaic devices to trap light without affecting the physical thickness of solar photovoltaic absorber layers and yielding new options for solar cell design.     

Ionic double layer of atomically flat gold formed on mica templates

Electrical impedance spectroscopy characterisations of gold surfaces formed on mica templates in contact with potassium chloride electrolytes were performed at the electric potential of zero charge over a frequency range of 6 × 10⁻³ to 100 × 10³ Hz. They revealed constant-phase-angle (CPA) behaviour with a frequency exponent value of 0.96 for surfaces that were also characterised as atomically flat using atomic force microscopy (AFM). As the frequency exponent value was only marginally less than unity, the CPA behaviour yielded a realistic estimate for the capacitance of the ionic double layer. The retention of the CPA behaviour was attributed to specific adsorption of chloride ions which was detected as an adsorption conductance element in parallel with the CPA impedance element. Significant variations in the ionic double layer capacitance as well as the adsorption conductance were observed for electrolyte concentrations ranging from 33 μM to 100 mM, but neither of these variations correlated with concentration. This is consistent with the electrical properties of the interface deriving principally from the inner or Stern region of the double layer.     

Electrochemical preparation of pyronin Y thin films on gold substrates

Cyclic voltammetry, chronoamperometry, UV‐vis absorption spectroscopy, fluorescence spectroscopy, FTIR spectroscopy, and AFM techniques have been employed to investigate pyronin Y thin films formed on Au(111) substrates by electrochemical oxidation of pyronin Y monomer. The medium used in the electropolymerization was an anhydrous acetonitrile solution containing 0.1M TBAClO₄ as supporting electrolyte. Anodic electropolymerization potential (1450 mV) of pyronin Y has been obtained from cyclic voltammetry data. Solid‐state electropolymerization of pyronin Y was performed by the potential‐controlled electrolysis technique. Chronoamperometry studies indicate that the adsorption of pyronin Y takes place in an instantaneous three‐dimensional nucleation and growth mechanism which is accompanied by random adsorption. UV‐vis absorption and fluorescence spectra of the electrolysis solution as a function of electrodeposition time show the adsorption of insoluble pyronin Y films on Au electrode surface. FTIR‐specular reflectance of a polymer coated Au electrode reveals that there is a possible C? C coupling in the formation of polymeric pyronin Y structure. A well ordered polymeric chain structure of pyronin Y on Au(111) has been observed from AFM data. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Surface morphology of adsorbed sulfur‐functionalized polystyrene thin film on gold on the basis of atomic force microscopic observation

Polystyrene thin film containing one‐terminal thiol (PS–SH) was spin‐coated and adsorbed from 0.1 to 0.001 wt % of polymer solution in toluene onto evaporated gold (Au) film supported on Si‐wafer substrate. The effect of polymer solution concentration on the aggregation structure of PS–SH thin films was determined on the basis of atomic force microscopic (AFM) observation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1248–1252, 2002     

Evolution of TiOx-SiOx nano-composite during annealing of ultrathin titanium oxide films on Si substrate

This paper discusses the formation of the TiO_x-SiO_x nano-composite phase during annealing of ultrathin titanium oxide films (~27 nm). The amorphous titanium oxide films are deposited on silicon substrates by sputtering. These films are important for high-k dielectrics and sensing applications. Annealing of these films at 750 °C in the O₂ environment (for 15–60 min) resulted in the polycrystalline rutile phase. The films exhibit Raman peaks at 150 cm⁻¹ (B_1g), 435 cm⁻¹ (E_g), and 615 cm⁻¹ (A_1g) confirming the rutile phase. The signature TO (1078 cm⁻¹) and LO (1259 cm⁻¹) infrared active vibrational modes of Si–O–Si bond confirms the presence of silicon-oxide. The X-ray photoelectron spectra of the TiO_x films show multiple peaks corresponding to Ti metal (453.8 eV); Ti⁴⁺ state (458.3 eV (Ti 2p_3/2) and 464 eV (Ti 2p_1/2)); and Ti³⁺ state (456.4 eV (Ti 2p_3/2) and 460.8 eV (Ti 2p_1/2)). The O1s XPS spectra peaks at 530–533 eV can be attributed to Ti–O and Si–O bonds of the TiO_x-SiO_x nano-composite phase in the annealed films. The depth profiling XPS study shows that the top surface of the annealed film is mainly TiO_x and the amount of SiO_x increases with the depth.     

Gravure printing of conductive particulate polymer inks on flexible substrates

A roto-gravure printing technique has been developed for conductive lines on paper and plastic films. Rotary-screen-printing was used to make comparative prints. The inks contained metal particles in an organic medium and were cured in temperatures of 70–120 °C, limited by the substrate durability. The following conductor line properties were characterised for different substrates: resistance, yield as a function of line width, coil inductance, folding endurance, adhesion, printed antenna properties and maximum current density. A printed resistance down to 50 mΩ/□ was obtained, with conductor lines 4–7 μm thick. Minimum line resolution and resistance were affected by smoothness of substrates. Adhesion properties were adequate for the studied components.     

Multiscale physical characterization of an outdoor-exposed polymeric coating system

Surface topography and gloss are two related properties affecting the appearance of a polymeric coating system. Upon exposure to ultraviolet (UV) radiation, the surface topography of a coating becomes more pronounced and, correspondingly, its gloss generally decreases. However, the surface factors affecting gloss and appearance are difficult to ascertain. In this article, atomic force microscopy (AFM) and laser scanning confocal microscopy (LSCM) measurements have been performed on an amine-cured epoxy coating system exposed to outdoor environments in Gaithersburg, Maryland. The formation of the protuberances is observed at the early degradation stages, followed by the appearance of circular pits as exposure continues. At long exposure times, the circular features enlarge and deepen, resulting in a rough surface topography and crack formation. Fourier Transform Infrared Spectroscopy (FTIR) study indicates that the oxidation and chain scission reactions are likely the origins of the surface morphological changes. The relationship between changes in surface roughness and gloss has been analyzed. The root mean square (RMS) roughness of the coating is related to nanoscale and microscale morphological changes in the surface of the coating as well as to the gloss retention. A near-linear dependence of RMS roughness with the measurement length scale (L) is found on a double logarithmic scale, i.e., RMS ∼ L ^f. The scaling factor, f, decreases with exposure time. The relationship between surface topography, on nano- to microscales, and the macroscale optical properties such as gloss retention is discussed. Moreover, a recent development in using an angle-resolved light scattering technique for the measurement of the specular and off-specular reflectance of the UV-exposed specimens is also demonstrated, and the optical scattering data are compared to the gloss and the roughness results.

Solvothermal Synthesis, Structure and Optical Property of Nanosized CoSb(3) Skutterudite

Binary skutterudite CoSb₃ nanoparticles were synthesized by solvothermal method. The nanostructuring of CoSb₃ material was achieved by the inclusion of various kinds of additives. X-ray diffraction examination indicated the formation of the cubic phase of CoSb₃. Structural analysis by transmission electron microscopy analysis further confirmed the formation of crystalline CoSb₃ nanoparticles with high purity. With the assistance of additives, CoSb₃ nanoparticles with size as small as 10 nm were obtained. The effect of the nanostructure of CoSb₃ on the UV–visible absorption and luminescence was studied. The nanosized CoSb₃ skutterudite may find application in developing thermoelectric devices with better efficiency.     

Atomic force microscopy and contact angle studies of polymerizable gemini surfactant admicelles on mica

Atomic force microscopy (AFM) was used to directly observe and characterize a polymer‐modified mica surface prepared using a polymerizable gemini surfactant. Normal tapping mode and contact mode AFM were used to image the treated mica surface morphologies in air and liquid environments, respectively. The root mean square (RMS) roughness of mica surfaces before and after surface modification and polymerization was analyzed from these scans. To determine the effect of styrene adsolubilization on the surfactant‐modified mica, AFM measurements of the modified mica were made at various styrene concentrations. Contact angle measurements were also made to further characterize the nature of the surfactant‐modified mica surface. The surface morphology and surface hydrophilicity were observed to be different for the modified mica after polymerization. In addition, the polymerized surface maintained its morphology after washing/desorption studies demonstrating the stability of the polymerized surfactant film. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

光纤表面金属化工艺的研究

提出了光通讯领域中镀金光纤的化学镀制备工艺,通过前处理及钯银活化、化学镀镍,再电镀金,获得了表面光滑、高锡焊接性能以及高附着力的镀金光纤,满足光通讯的要求.研究探讨了前处理以及活化工艺对镀金光纤性能的影响.     

Quantitative Analysis of Fractured Surfaces in PMnEDM-Based Dental Adhesive Bonds by Use of Optical Microscopy

The aim of this work was to characterize quantitatively the contribution of different failure modes during shear bond strength (SBS) measurements and to correlate both those sets of results. Four experimental dental adhesive systems were used to join dental composite with cobalt–based alloy plate. The samples were subjected to SBS measurements according to International Organization for Standardization (ISO) procedure and resulting fractures were examined by optical microscopy, including computer-aided processing of the images, to yield quantitative contributions of adhesive and cohesive failures. Identification of particular failure modes as well as quantitative determination of respective contributions appeared to be possible. The data were processed by statistical methods including Shapiro-Wilk and Mann-Whitney U tests. The results of fractographic analysis were found to correlate with SBS values. Contribution of adhesive failures appeared to determine the strength of adhesive bonds. A new dental adhesive system based on PM2EDM monomer exhibited a very good performance in respect to the metal alloy.     

TiO2在不同基质上光催化活性的比较

研究了不同基质对纳米TiO2光催化活性的影响。采用甲基橙作为脱色对象,以脱色速率常数作为衡量光催化活性的标准,发现金属基质更有效,且对TiO2光催化活性有明显的协同作用,其中在镀锌白铁基质上的光催化效率最高。     

Electrodeposition of cobalt on gold during voltammetric cycling

Co was electrodeposited on Au(111) from solutions of CoSO₄ in 0.5 mM H₂SO₄. STM showed that the electrodeposition started at an underpotential of 0.26 V. In cathodic sweeps voltammograms exhibited a low cathodic peak C1 at an overpotential of 0.1 V and a large cathodic peak C2 at an overpotential above 0.2 V. From the cathodic charge it was estimated that at peak C1, the deposit was about one monolayer thick. AFM indicated the presence of flat deposits at peak C1, and of numerous islands at peak C2, demonstrating massive nucleation and growth at the latter peak. It is suggested that peak C1 may be associated with a hindrance of nucleation processes due to adsorption of chemical species, probably of hydrogen H_ad. During a reverse anodic sweep from C2, anodic peaks A1 and A2 were observed. Peak A1 was evidently associated with anodic oxidation of electrodeposited cobalt, whereas peak A2 at nobler potentials, probably resulted from oxidation of hydrogen, incorporated into the Co electrodeposit.     

Electrochemical preparation and characterization of nickel and zinc-modified poly-2-aminothiazole films on mild steel surface and their corrosion inhibition performance

Poly-2-aminothiazole (pAT) was electrochemically synthesized on a mild steel (MS) specimen from 0.3 M aqueous ammonium oxalate solution containing 0.01 M 2-aminothiazole (2-AT) using cyclic voltammetry technique. The synthesized polymer film was then modified by electrodeposition of 100 μg cm⁻² Ni (MS/pAT–Ni) and Zn (MS/pAT–Zn) on top of the polymer surface. The surface morphologies of the polymer films were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The elemental analysis of the surface films was performed by energy dispersive X-ray spectroscopy (EDX). The effectiveness of the coatings in preventing corrosion of MS in 3.5% NaCl solution was assessed using electrochemical techniques. It was found that the obtained coatings were adherent to the steel surface. The pAT film provided a good corrosion protection against the attack of corrosive environment. Moreover, the modification of pAT film by deposition of Ni and Zn on top of the polymer surface significantly enhances the corrosion protection performance of the polymer film by exhibiting an improved barrier effect against the attack of corrosive environment. The surface morphologies and protection ability of the layers were found to be dependent on the type of deposited metal.     

Effect of mica addition on the properties of natural rubber and polybutadiene rubber vulcanizates

The rheometric, mechanical, and dynamic mechanical properties as well as fracture surfaces of natural rubber–mica and polybutadiene rubber–mica vulcanizates were studied. Mica was used in the range of 0–30 phr and the rheometric study was carried out at 160°C. The results indicate that the mechanical properties are improved as filler addition increases. Dynamic mechanical testing was used to analyze the observed mechanical behavior. The two elastomers showed different fracture behaviors. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2156–2162, 2003     

Structure–property relationships of thermoplastic polyurethane elastomers based on polycarbonate diols

The phase-separation behavior and morphology of polycarbonate-based polyurethanes were investigated as a function of the soft-segment molecular weight and chemical structure and the 4,4′-diphenylmethane diisocyanate/1,4-butanediol based hard-segment contents. Polarized optical microscopy and atomic force microscopy images showed that the surface morphologies changed as the soft-segment molecular weight and hard-segment content varied and also when the sample preparation conditions were modified. An increase in the soft- and hard-segment lengths led to increased phase separation with respect to the lower molecular weight soft segment, and this showed an interlocked and connected morphology of intermixed soft and hard domains. The surface morphology of phase-separated polyurethanes with hard segments composed of more than four to five 4,4′-diphenylmethane diisocyanate units contained globular hard-segment domains formed by spherulites, in which the size and connectivity between the branched lamellae changed with the hard-segment size. Interlamellar areas related to the soft segment were seen in the spherulites. Variations in the hard-segment spherulites were observed for polyurethanes based on soft segments of different molecular weights. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

聚碳酸酯光学性能应用及改进研究进展

概述了光学级聚碳酸酯结构与光学性能的关系和其在光学领域的应用,对其光学异向性产生的原因进行了讨论,并对改善聚碳酸酯光学异向性的途径进行了归纳,通过采用共聚、共混方法可使聚碳酸酯的双折射得到有效的降低。     

Influence of mixing procedures and mica addition on properties of NR/BR vulcanizates. I

Elastomeric compositions of natural rubber (NR) and polybutadiene rubber (BR) in a 1 : 1 ratio (w/w), with mica in the range 0–30 phr, were investigated. For all compositions the same formulation was used but two different additives incorporation sequences were followed. The results of the tests showed that the mechanical performance is sequence‐dependent, as the two elastomers have very different rheometric characteristics. It was also observed that mica, when present in amounts of 20 and 30 phr, improves the mechanical properties. Scanning electron microscopy (SEM) permitted the observation of the fracture behavior of each composition, and dynamic mechanical thermal analysis (DMTA) suggested different migration tendencies of the additives in each phase, thus corroborating the differences found for the mechanical properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1575–1585, 2004