Search results for "polarization [Upsilon(9460)]"
showing 10 items of 915 documents
The influence of composition on band gap and dielectric constant of anodic Al-Ta mixed oxides
2015
Al-Ta mixed oxides were grown by anodizing sputter-deposited Al-Ta alloys of different composition. Photocurrent spectra revealed a band gap, Eg, slightly independent on Ta content and very close to that of anodic Ta2O5 (∼4.3 eV) with the exception of the anodic film on Al-10at% Ta, which resulted to be not photoactive under strong anodic polarization. The photoelectrochemical characterization allowed to estimate also the oxides flat band potential and to get the necessary information to sketch the energetic of the metal/oxide/electrolyte interfaces. Impedance measurements allowed to confirm the formation of insulating material and to estimate the dielectric constant of the oxides, which re…
Enhanced light confinement in a triangular aperture: Experimental evidence and numerical calculations
2005
We have recently demonstrated that the electric near-field emerging from a triangular aperture at the tip of a metal-coated tetrahedron of glass exhibits a highly confined and intense spot when the light incident from within the glass body is polarized perpendicularly to one edge of the aperture [Naber et al., Phys. Rev. Lett. 89, 210801 (2002)]. Here we present additional experimental material and a theoretical confirmation of this near-field optical effect. Based on the model of a triangular aperture in a planar metal film, we studied the influence of aperture size and film material on the field distribution. Even though our theoretical model is rather simplified as compared to the experi…
Semiconducting properties of passive films and corrosion layers on weathering steel
2020
Abstract Anodic films were grown on Weathering Steel by potentiostatic polarization in slightly alkaline solution. The photoelectrochemical results reveal that they are n-type iron oxide with Eg = 2.0 eV. Rust layer grown by atmospheric corrosion are n-type semiconductors with a band gap higher than that estimated for the anodic film attributed to the formation of γ-lepidocrocite. The electrochemical impedance spectra allow to evidence that rust layers have a higher conductivity with respect to anodic films due to the presence of highly doped iron oxide layers. The use of Mott-Schottky theory to model the dependence of oxide capacitance as function of potential is critically discussed.
The effect of electrochemically simulated titanium cathodic corrosion products on ROS production and metabolic activity of osteoblasts and monocytes/…
2006
Nowadays aseptic loosening is the most common cause of orthopaedic implant failure. Some of its reasons have already been described up to now; however, others remain still hypothetical. Besides the inflammatory response to wear particles originating at different sources, the role of reactive oxygen species as products of cellular reactions and/or as a result of the process of corrosion of an implant leading to implant failure has recently been discussed too. In the present study, we used a galvanostatic polarization to simulate the cathodic partial reaction of the corrosion process at a titanium alloy surface. With respect to cells occurring at the interface of a metal implant, the behaviou…
Optical field-induced surface-relief micropatterning of amorphous chalcogenide thin films
2015
The study of direct recording of the surface relief gratings on amorphous chalcogenide thin (2.5 to 5 μm films is presented by three different recording setups. Recording was performed on As2S3 by 532-nm wavelength laser light. Additionally, the evolution of a surface relief in dependence from the recording time and polarization has been investigated in detail and for the first time, the mass transfer process has been explained from the point of view of the photoinduced birefringence. The role of photoinduced plasticity in the formation of surface relief in amorphous chalcogenides during holographic recording has been discussed.
The influence of molecular properties of additives on the stability of polyethylene in high electric fields
2003
Results are presented of studies of some molecular properties, i.e., dipole moment, total polarizability, and electronic polarizability, of dihalide and diamine derivatives of phenylene, p,p'-bi-phenylene and carbazole, which are used as additives for physical modification of polyethylene. The diffusion coefficients of these substances from a polyethylene matrix were estimated, and the stability of modified polyethylene in high electric fields (50 Hz) was found. The mechanism of action of high-voltage stabilizers in polyethylene was verified. >
Effects of Bending on Raman-active Vibration Modes of Carbon Nanotubes
2008
We investigate vibration modes and their Raman activity of single-walled carbon nanotubes that are bent within their intrinsic elastic limits. By implementing novel boundary conditions for density-functional based tight-binding, and using non-resonant bond polarization theory, we discover that Raman activity can be induced by bending. Depending on the degree of bending, high-energy Raman peaks change their positions and intensities significantly. These effects can be explained by migration of nodes and antinodes along tube circumference. We discuss the challenge of associating the predicted spectral changes with experimental observations.
PEM electrolyzer characterization with carbon-based hardware and material sets
2021
Abstract The research and development of proton exchange membrane water electrolysis (PEMWE) is an upcoming and growing area due to a rising interest in hydrogen as an energy carrier. Operating conditions are harsher than in a fuel cell system, particularly because the potentials required for the oxygen evolution reaction are significantly higher. In commercial water electrolysis systems, this is compensated by typically using titanium material sets that are often protected against oxidation through coating processes. Such material choices make small scale research hardware and porous transport layers expensive and difficult to source. In this work, we show that the stability of traditional…
<title>Holographic recording of subwavelength structures in amorphous chalcogenide thin films</title>
2005
Holographic recording of surface-relief and refiactive-index-modulated gratings with a period ranging from 0.15 to 1 μm in thin amorphous chalcogenide films of As-S-Se and As2S3 is studied. The profile of the surface-relief gratings is measured by atomic force microscopy. By structuring the As-S-Se films with the subwavelength-period surface-relief gratings their reflectivity is decreased from 25-30% to less than 2%. In the refractive-index-modulated As2S3 films polarization effects are revealed. It is shown that the angular selectivity of the holographic recording in amorphous chalcogenide thin films can be substantially improved by decreasing the grating period.© (2005) COPYRIGHT SPIE--Th…
Effect of Organic Tin Compounds on Electric Properties of Model Membranes
2006
The objective of the present work was to investigate the effect of selected organic tin compounds and potassium chloride (used as a reference substance) on the trans-membrane electric voltage and electric resistance of model membranes, the latter being nitrocellulose filters impregnated with butylene ester of lauric acid. The increasing KCl concentration (in the measurement chambers) caused a rapid rise of the negative trans-membrane voltage, whose value stabilized afterwards. In the case of (C3H7)3SnCl an abrupt maximum of the negative voltage was observed followed by a monotonic drop to zero. In the case of highest concentrations of this compound the voltages, after having reached zero, c…