铝箔在盐酸中的交流电侵蚀的研究—Ⅱ.50周交流电正半周侵蚀

五种不同纯度电容器用铝箔(99.97—99.999%Al)在盐酸中用50周交流电正半周进行侵蚀。由于侵蚀膜是在断电半周低pH值下形成的,属透明钝化型薄膜,不堵塞侵蚀孔,因此不出现纯交流电侵蚀时的"掉粉"、"减薄"现象。实验结果表明,侵蚀形态以及表面积扩大率与箔的纯度,也即其自钝化能力有关。用电位波形图解释了得到的现象。     

Impedance measurements on QLED devices: analysis of high-frequency loop in terms of material properties

Electrochemical impedance spectroscopy is used to study red and green quantum-dot light-emitting diodes devices. The high-frequency loop is interpreted in terms of the thickness, dielectric constant, and resistivity distribution of the hole-injection layer. The analysis employed the device capacitance obtained from a measurement model analysis, the film thickness measured by scanning electron microscopy, and an interpretation of the impedance based on a power-law model. Impedance measurements performed on hole-transport–only devices yielded results that were consistent with the interpretation of the high-frequency capacitive loop in terms of the properties of the hole-injection layer.

     

铝箔在盐酸中的交流电侵蚀的研究—Ⅰ.50周交流电侵蚀

研究了电解电容器用铝箔在5M HCl中用50周交流电侵蚀时温度、电流密度、铝箔纯度以及H₂SO₄添加剂等因素对表面积扩大率K值的影响。得到高K值的关键是得到高质量的侵蚀膜,SO₄^2-是成膜所必需的。用剥膜称重法得到了不同条件下单位真实表面积上的膜重,结合电位波形图解释了一系列现象。侵蚀过程中出现的表面大量掉落黑粉,箔厚减薄、比容不再随电量而增加的现象与侵蚀孔中pH过高、侵蚀膜(氧化铝)水化程度高、体积大因而堵塞小孔有关。保证有足够的H⁺扩散进入孔中是得到高K值的又一关键。     

Quantitative determination of element distributions in silicon based thin film solar cells using SNMS

The determination of elemental distributions in thin film solar cells based on amorphous silicon using electron beam SNMS is possible by quantifying the measured ion intensities. The relative sensitivity factors (RSFs) for all elements measured have to be known. The RSFs have been determined experimentally using implantation and bulk standards with known concentrations of the interesting elements. The measured RSFs have been compared with calculated RSFs. The model used for the calculation of the RSFs takes into account the probability for electron impact ionization and the dwell time of the neutrals inside the postionization region. The comparison between measured and calculated RSF shows, that this model is capable to explain the RSFs for most elements. Differences between calculated and measured values can be explained by the formation of hydride and fluoride molecules (in case of H and F) and influences of the angular distribution of the sputtered neutrals in case of Al. The experimentally determined RSFs have been used for a quantification of depth profiles of the i-, buffer-, p- and front contact layers of a-Si solar cells.     

Quantitative determination of element distributions in silicon based thin film solar cells using SNMS

The determination of elemental distributions in thin film solar cells based on amorphous silicon using electron beam SNMS is possible by quantifying the measured ion intensities. The relative sensitivity factors (RSFs) for all elements measured have to be known. The RSFs have been determined experimentally using implantation and bulk standards with known concentrations of the interesting elements. The measured RSFs have been compared with calculated RSFs. The model used for the calculation of the RSFs takes into account the probability for electron impact ionization and the dwell time of the neutrals inside the postionization region. The comparison between measured and calculated RSF shows, that this model is capable to explain the RSFs for most elements. Differences between calculated and measured values can be explained by the formation of hydride and fluoride molecules (in case of H and F) and influences of the angular distribution of the sputtered neutrals in case of Al. The experimentally determined RSFs have been used for a quantification of depth profiles of the i-, buffer-, p- and front contact layers of a-Si solar cells.     

Study of reactive ion etching of Si and SiO2 for CFxCl4−x gases

A parametric study of the etching of Si and SiO₂ by reactive ion etching (RIE) was carried out to gain a better understanding of the etching mechanisms. The following fluorocarbons (FCs) were used in order to study the effect of the F-to-Cl atom ratio in the parent molecule to the plasma and the etching properties: CF₄, CF₃Cl, CF₂Cl₂, and CFCl₃ (FC-14, FC-13, FC-12, and FC-11 respectively). The Si etch rate uniformity across the wafer as a function of the temperature of the wafer and the Si load, the optical emission as a function of the temperature of the load, the etch rate of SiO₂ as a function of the sheath voltage, and the mass spectra for each of the FCs were measured. The temperature of the wafer and that of the surrounding Si load strongly influence the etch rate of Si, the uniformity of etching, and the optical emission of F, Cl, and CF₂. The activation energy for the etching reaction of Si during CF₄ RIE was measured. The etch rate of Si depends more strongly on the gas composition than on the sheath voltage; it seems to be dominated by ion-assisted chemical etching. The etching of photoresist shifted from chemical etching to ion-assisted chemical etching as a function of the F-to-Cl ratio and the sheath voltage. The etch rate of SiO₂ depended more strongly on the sheath voltage than on the F-to-Cl ratio.     

Reactive species generated during wet chemical etching of silicon in HF/HNO3 mixtures

The role of intermediate species generated during wet chemical etching of silicon in a HF-rich HF/HNO3 mixture was studied by spectroscopic and analytical methods at 1 degrees C. The intermediate N2O3 was identified by its cobalt blue color and the characteristic features in its UV-vis and Raman spectra. Furthermore, a complex N(III) species (3NO+.NO3-) denoted as [N4O6(2+)] is observed in these solutions. The time-dependent decay of the N(III) intermediates, mainly by their oxidation at the liquid-air interface, serves as a precondition for the study of the etch rate as function of the intermediate concentration measured by Raman spectroscopy. From a linear relationship between etch rate and [N4O6(2+)] concentration, NO+ is considered to be a reactive species in the rate-limiting step. This step is attributed to the oxidation of permanent existing Si-H bonds at the silicon surface by the reactive NO+ species. N2O3 serves as a reservoir for the generation of NO+ leading to a complete coverage of the silicon surface with reactive species at high intermediate concentrations. As long as this condition is valid (plateau region), the etch rate is constant and yields a smooth silicon surface upon completion of the etching. If the N2O3 concentration is insufficient to ensure a coverage of the Si surface by NO+, the etch rate decreases linearly with the N2O3 concentration and results in a roughening of the etched silicon surface (slope region).     

Direct observation of surface-profile effects on X-ray-photoelectron angular distributions

The first direct observations of surface-profile effects on X-ray-photoelectron angular distributions are reported. Ratios of Al 2p (oxide) and Al 2p (metal) peak intensities were measured at various electron emission angles for two different types of specimens consisting of an aluminum substrate with a surface oxide layer. For triangular-periodic diffraction grating surfaces with 10°, 20°, and 43° blaze angles, pronounced structure was observed in the ratio angular distributions; theoretical calculations based upon the ideal grating geometries furthermore reproduce all of the features found experimentally. For unidirectionally-polished aluminum specimens, ratio angular distributions measured perpendicular and parallel to the polishing grooves were found to be markedly different, with more oxide enhancement being possible at low electron emission angles for the parallel orientation; this finding is also qualitatively consistent with theory.     

Reactions of dental enamel with superficially applied fluorides: electron spectroscopic investigations

Electron spectroscopy combined with argon ion etching was applied for studying reactions of fluoride with dental enamel. Using this assembly to alternately record the spectra and etch the surface, depth profiles of topmost surface enamel can be obtained. The hyperfine depth resolution of the technique provided new information on the distribution of fluoride and its reaction products in the outermost layers of dental enamel.     

双电层电容器电化学阻抗谱的实验研究(英文)

电化学阻抗谱(EIS)是一种很有用的研究电化学性能的技术.理想的双电层电容器(EDLC)阻抗谱的尼奎斯特图由中高频的45°线和低频的与实轴垂直的直线组成,可以用孔径分布-传输线模型来解释.然而,在研究工作中还发现,在阻抗谱的高频区出现了半圆弧区域,为此,提出的等效模型认为半圆弧可以归因于活性材料之间的接触电阻和接触电容,以及电极与集流体之间的接触电阻与接触电容.还研究了充电过程、活性炭和电解液的电导率、导电添加剂和粘结剂的含量、隔膜、活性物质附载量和极片加压等因素对阻抗谱的影响.其中,充电截止电压、活性炭的电导率、导电添加剂的含量和极片加压对半圆弧部分影响较为显著.     

双电层电容器电化学阻抗谱的实验研究

电化学阻抗谱(EIS)是一种很有用的研究电化学性能的技术. 理想的双电层电容器(EDLC)阻抗谱的尼奎斯特图由中高频的45°线和低频的与实轴垂直的直线组成, 可以用孔径分布-传输线模型来解释. 然而, 在研究工作中还发现, 在阻抗谱的高频区出现了半圆弧区域, 为此, 提出的等效模型认为半圆弧可以归因于活性材料之间的接触电阻和接触电容, 以及电极与集流体之间的接触电阻与接触电容. 还研究了充电过程、活性炭和电解液的电导率、导电添加剂和粘结剂的含量、隔膜、活性物质附载量和极片加压等因素对阻抗谱的影响. 其中, 充电截止电压、活性炭的电导率、导电添加剂的含量和极片加压对半圆弧部分影响较为显著.     

Study of gamma irradiation effects on the etching and optical properties of CR-39 solid state nuclear track detector and its application to uranium assay in soil samples

The gamma irradiation effects in the dose range of 2.5?C43.0 Mrad on the etching and optical characteristics of CR-39 solid state nuclear track detector (SSNTD) have been studied by using etching and UV?CVisible spectroscopic techniques. From the measured bulk etch rates at different temperatures, the activation energies for bulk etching at different doses have also been determined. It is seen that the bulk etch rates increase and the activation energies for bulk etching decrease with the increase in gamma dose. The optical band gaps of the unirradiated and the gamma -irradiated detectors determined from the UV?CVisible spectra were found to decrease with the increase in gamma dose. These results have been explained on the basis of scission of the detector due to gamma irradiation. The present studies can be used for the estimation of gamma dose in the range of 2.5?C43.0 Mrad and can also be used for estimating track registration efficiency in the presence of gamma dose. The CR-39 detector has also been applied for the assay of uranium in some soil samples of Jammu city.     

硝酸刻蚀银表面的增强拉曼光谱及其在表面化学中的应用

最近,我们摸索出的硝酸刻蚀法制备有SERS(Surface Enhanced Raman Scattering,表面增强拉曼散射)活性的银表面,有良好的热稳定性,且费用低廉,预期在研究金属表面反应、催化和金属-聚合物界面结构等方面可发挥作用。在展示了这一新方法具有极高的表面增强因子后,本文介绍用该法研究吸附质的自集合(self-assembly)和表面取向结果。     

Molecular structure and vibrational spectra of 1,3-bis(4-pyridyl)propane by quantum chemical calculations

The experimental and theoretical study on the structures and vibrations of 1,3-bis(4-pyridyl)propane are presented. The FT-IR and Raman spectra of molecule have been measured. The optimized geometric bond lengths have been obtained by DFT show the best agreements with experimental values. The harmonic vibrational frequencies were calculated and scaled values have been compared with experimental FT-IR and FT-Raman spectra. Majority of the computed wavenumbers were found to be in good agreement with experimental observations. A complete assignment of the fundamentals was proposed based on the total energy distribution (TED) calculation.     

Analysis of impedance spectra of a pitted Inconel alloy 600 electrode in chloride ion-containing thiosulfate solution at temperatures of 298–573 K

In the present work, impedance spectra of a pitted Inconel alloy 600 electrode were analysed in aqueous 0.1 M Na₂S₂O₃+0.1 M NaCl solution at elevated solution temperatures of 298–573 K and at pressures of 0.1–8 MPa in terms of pit size distribution, fractal dimension and surface roughness in sequence as the solution temperature rose. From impedance spectra of the Nyquist plot obtained from the pitted specimen exposed to solutions at temperatures of 60–150°C, a constant phase element (CPE) was observed in the frequency range from 10³ to 1 Hz. Especially, it was found that the impedance spectra were divided into two sections, i.e. a first CPE with a smaller slope in the higher frequency range and a second CPE with a larger slope in the lower frequency range. The occurrence of the two kinds of CPE results from a transition of ion diffusion through the pit to ion accumulation at the pit bottom, which is caused by double-layer charging at the pit bottom and prior double-layer charging at the pit wall. Impedance spectra were simulated in terms of pit size distribution and values of the fractal dimension of the pits as a function of solution temperature to compare with those spectra measured experimentally. The spectra were simulated based upon the conventional transmission line model for a cylindrically shaped pit at 60 °C and on the basis of a modified transmission line model for the triadic Koch construction at 100 °C and for the quadratic Koch construction at 150 °C. The modified transmission line model takes into account the resistive and capacitive elements in the lateral direction as well as those in the downward direction of the three-dimensional Koch constructions. Above 200 °C the Nyquist plots were found to be depressed more noticeably from a perfect semicircular form with increasing solution temperature. This is due to the increase in the surface roughness of the specimen by the formation and growth of the pits. Electronic Publication     

AC impedance and state-of-charge analysis of a sealed lithium-ion rechargeable battery

A 7.2 V, 1.25 Ah sealed lithium-ion rechargeable battery has been studied for estimating its state-of-charge (SOC) by AC impedance. The dispersion of impedance data over the frequency range between 100 kHz and 25 mHz comprises an inductive part and two capacitive parts. As the inductive behaviour of the battery is attributed to the porous nature of the electrodes, only the capacitive components have been examined. The data obtained at several SOC values of the battery have been analyzed by a non-linear least-squares fitting procedure. The presence of two depressed semicircles in the capacitive region of the Nyquist plots necessitated the use of an electrical equivalent circuit containing constant phase elements instead of capacitances. The impedance parameters corresponding to the low-frequency semicircle have been found useful for predicting the SOC of the battery, mainly because the magnitude of these parameters and their variations are more significant than those of the high-frequency semicircle. The frequency maximum (f _max) of the semicircle, the resistive component (Z′) corresponding to f _max, the phase angle (φ) in the 5.0 Hz–0.1 Hz frequency range, the equivalent series resistance (R _s) and the equivalent series capacitance (C _s) have been identified as suitable parameters for predicting the SOC values of the lithium-ion battery. Received: 23 September 1998 / Accepted: 22 February 1999     

A density functional study of 1,1,5‐tris(4‐dimethylaminophenyl)‐3‐methyl‐divinylene

The optimized molecular structural parameters and UV‐vis, IR and Raman spectra of a dye molecule with an open formula of 1,1,5‐Tris(4‐dimethylaminophenyl)‐3‐methyl‐divinylene are determined by means of density functional theory (DFT) calculations using B3LYP/6‐31G** formalism. Neutral and cationically charged molecules are used for DFT computations. C? C, C?C, and N? C bond distances of dimethylaminophenyl groups of the dye molecule are in reasonable agreement with the experimental and theoretical C? C, C?C, and N? C bond lengths of the group reported in the literature. Because Vis‐NIR region is near UV‐Vis region in the electromagnetic spectra, calculated maximum wavelengths of UV‐vis spectra are close to those of the experimental VIS‐NIR spectra reported. C?C stretching frequencies calculated for dimethylaminophenyl, alkene, and benzene ring groups are also in good agreement with experimentally reported values. All calculated frequencies fall within 2.2% of the experimental frequency region. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Characterisation of the aluminium–electropolymerised poly(3,4-ethylenedioxythiophene) system

Poly(3,4-ethylenedioxythiophene) (PEDOT) was electropolymerised on aluminium substrates. The Al/Al oxide/PEDOT junction was studied by electrochemical impedance spectroscopy, comparing the impedance response of the polymer film in oxidised, neutral and reduced form. The p- and n-doping behaviour of the PEDOT films was studied by in situ external reflection Fourier transform infrared spectroscopy during stepwise potential cycling of the films. The Al surface underneath the polymer was analysed with X-ray photoelectron spectroscopy. The impedance spectra indicate that an insulating layer between the metal and the polymer grows thicker during doping of the polymer film. The other techniques used suggest that this interfacial layer consists mainly of Al oxides and fluorides. Neither the conductivity nor the dopability of the polymer is notably affected by the growing of this insulating interfacial layer, which makes the concept of PEDOT electropolymerised on Al promising from an organic electronics applications point of view.     

Threshold Al KLL Auger spectra of oxidized aluminium foils

Threshold Al KLL Auger electron spectroscopy and K‐edge x‐ray absorption fine structure spectroscopy have been used to examine technical purity (99.5%) aluminium foil before and after chemical treatment that altered the thickness and degree of hydroxylation of the oxidized layer. Comprehensive surface chemical characterization was effected by means of monochromatized Al Kα‐excited photoelectron spectroscopy. Threshold Al KL_{2, 3}L_{2, 3} spectra were obtained for three of the foils investigated and these spectra were in broad agreement with those observed previously for pure Al foil. The relative intensities of the spectral components for two of the foils were clearly consistent with the previously proposed assignment of the resonantly enhanced Auger component, situated between those arising from the metal and Al(III) oxide, to a thin interfacial layer. The threshold Auger spectra from the aluminium foil bearing the thickest and most hydroxylated oxidized layer were not obviously consistent with the interfacial layer model but O K‐edge spectra revealed that this surface layer was fundamentally different from the others and could have had a greater interfacial surface area. Copyright © 2003 John Wiley & Sons, Ltd.     

Linking optical and electrical small amplitude perturbation techniques for dynamic performance characterization of dye solar cells

This paper unifies the analytical models used widely but thus far mostly separately for electrical and optical small amplitude perturbation measurements of nanostructured electrochemical dye solar cells (DSC): electrochemical impedance spectroscopy (EIS), intensity-modulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS). The models are linked by expressing the kinetic boundary condition used for solving the time-dependent continuity equation of electrons in IMPS and IMVS analysis in terms of the series and parallel impedance components found in the complete equivalent circuit impedance model of DSC. As a result, analytical expressions are derived for potentiostatic IMPS and galvanostatic IMVS transfer functions of complete DSCs that are applicable at any operating point along the solar cell current-voltage (IV) curve. In agreement with the theory, impedance spectrum calculated as a ratio of IMVS and IMPS transfer functions measured near the maximum power point matches exactly with the impedance spectrum measured directly with EIS. Consequently, both IMPS-IMVS and EIS yield equal estimates for the electron diffusion length. The role of the chemical capacitance of the nanostructured semiconductor photoelectrode in the interpretation of the so-called RC attenuation of the IMPS response is clarified, as well as the capacitive frequency dispersion in IMPS and IMVS.