Search results for " capacitance"
showing 8 items of 38 documents
The Effect of Anodizing Bath Composition on the Electronic Properties of Anodic Ta-Nb Mixed Oxides
2022
Anodic oxides were grown to 50 V on Ta-Nb sputtering deposited alloys, with high Nb content, in acetate ions containing an aqueous solution to study the effect of the anodizing bath composition on anodic layers’ dielectric properties. Photoelectrochemical measurements proved the presence of a photocurrent in the band gap of photon energy lower than oxides, due to optical transitions involving localized electronic states as a consequence of acetate ions incorporation. Flat band potential value estimates assessed the insulating nature of the anodic oxides grown in the acetate buffer solution. Differential capacitance measurements showed that the highest capacitance value was measured for the …
Numerical approach for signal delay in general distributed networks
2003
The authors consider a general network with telegraph equations modelling distributed elements and having, additionally, nonlinear capacitors. A global asymptotic exponential stability of the solution is given. A simple computable upper bound of the delay time is given. Numerical examples illustrate the usefulness of the results. >
Assessing Field and Laboratory Calibration Protocols for the Diviner 2000 Probe in a Range of Soils with Different Textures
2016
Frequency domain reflectometry (FDR) downhole sensors have been increasingly used for soil moisture field monitoring because they allow measurement, even continuously, along a soil profile. Moreover, they can also be installed with minimal soil disturbance around the access tube. The objectives of the paper were to assess the field and laboratory calibration protocols for a FDR capacitance probe (Diviner 2000) for a range of soils characterized by different particle size distributions and shrink/swell potential and to propose a practical and effective protocol on the basis of undisturbed soil samples, accounting for soil shrinkage/swelling processes characterizing swelling clay soils. The e…
Direct Metal‐Free Chemical Vapor Deposition of Graphene Films on Insulating Substrates for Micro‐Supercapacitors with High Volumetric Capacitance
2019
Direct, metal‐free synthesis of graphene films on insulating substrates in a controlled manner is of great importance for applications in (opto)electronic and energy storage devices. Graphene films are fabricated on fused silica substrates without metal catalyst via chemical vapor deposition (CVD), using propionic acid as a carbon source. Film‐thickness is readily adjustable between 5 and 45 nm by changing the deposition time and flow rate of the precursor, displaying sheet resistance in the range of 0.27–1.86 kΩ□−1. The resulting graphene films are directly integrated into micro‐supercapacitors without film transfer or liquid‐phase processing, and demonstrate ultrahigh operation rates up t…
Cover Picture: Direct Metal‐Free Chemical Vapor Deposition of Graphene Films on Insulating Substrates for Micro‐Supercapacitors with High Volumetric …
2019
Photon Scanning Tunneling Microscopy and Reflection Scanning Microscopy
1991
The Photon Scanning Tunneling Microscope (PSTM) is the photon analogue to the Electron Scanning Tunneling Microscope (ESTM). It uses the evanescent field due to the total internal reflection (TIR) of a light beam in a prism modulated by a sample attached to the prism. The exponential decay of the evanescent field is characterized by the penetration depth dp and depends on the angle of incidence θ, the wavelength and polarization of the incident beam. Changes in intensity are monitored by a probe tip scanned over the surface, and the data are processed to generate an image of the sample. Images produced by a prototype instrument are shown to have a vertical resolution of about 3 A and a late…
Analysis of adsorption of phospholipids at the 1,2-dichloroethane/water interface by electrochemical impedance spectroscopy: A study of the effect of…
2007
Abstract The adsorption behaviour of a series of phosphatidylcholines (PCs) with saturated carbon chains of different length (DLPC, DPPC, DSPC, DAPC, and DBPC) at the electrified 1,2-dichloroethane/water interface was studied by measuring electrochemical impedance spectroscopy at the polarized interface. Two different trends in the interfacial capacitance were observed for any of the PCs the capacity dependence on the applied potential: strong adsorption occurs at negative potential with a marked decrease of C ( E ); increase of capacity is observed at positive potentials. It is demonstrated that the interfacial lipid adsorption was dependent on phospholipid concentration, applied potential…