掠射椭偏术对K_4〔Fe(CN)_6〕/K_3〔Fe(CN)_6〕电极反应的研究

提出掠射椭圆偏振测试技术的实验方案,应用该掠射式技术结合循环伏安法研究了在镀有Ｉｎ２Ｏ３玻璃片上进行的Ｋ４〔Ｆｅ（ＣＮ）６〕／Ｋ３〔Ｆｅ（ＣＮ）６〕电极反应．结果证明：掠射椭圆偏振术可在电化学反应过程中现场测定椭圆偏振参数及其变化规律,这些规律与所发生的表面电化学反应规律相对应,由此可以对电极体系进行研究;现场掠射椭圆偏振术还能用于分析表面扩散层的性质,弥补其它界面研究方法的缺陷．     

“电极/溶液”界面的椭圆偏振测量技术研究进展

椭圆偏振测量技术是通过解析偏振光束在界面上或薄膜中反射或透射时偏振状态的变化,获取界面或薄膜的厚度、复折射率等性质的一种光学方法,是一种高灵敏度、非破坏性的原位实时表征技术,被广泛应用于“电极/溶液”界面的研究. 本文简要介绍了椭圆偏振测量技术的基本原理及其最新发展,并着重评述了能源电化学、材料电化学、电分析与生物电化学等领域中,应用椭圆偏振测量技术研究“电极/溶液”界面的现状.     

氯化2,3,5-三苯基-2H-四唑及2,4,6-三(2-吡啶基)-s-三嗪在1mol/L HCl中对Q235碳钢的缓蚀作用及机理的研究(Ⅱ)

通过x射线光电子能谱(XPS)、椭圆偏振原位测试考察了氯化2,3,5-三苯基-2H-四唑(TTC),2,4,6-三(2-吡啶基)-s-三嗪(TPT)分子在1 mol/L HCI中对碳钢表面的缓蚀作用,并从微观上对二者的缓蚀机理进行探讨.XPS测试结果显示,由C,N元素的1s特征峰产生的化学位移及其积分峰面积表明TTC,TPT分子在金属表面产生了有效抑制腐蚀的保护层;由椭圆偏振原位测试并结合动电位极化曲线测试,考察了TTC,TPT分子对金属表面腐蚀反应的抑制程度,并得到了相位差等参量,结果表明二者在金属表面形成了具有缓蚀作用的覆盖层.     

氯化2,3,5-三苯基-2 氢-四唑(TTC)及2,4,6-三(2-吡啶基)-s -三嗪(TPT)在1mol/L HCl 中对Q235碳钢的缓蚀作用及机理的研究(Ⅱ)

通过X射线光电子能谱(XPS)、椭圆偏振原位测试考察了氯化2,3,5-三苯基-2H-四唑(TTC), 2,4,6-三(2-吡啶基)-s-三嗪(TPT)分子在1 mol/L HCl中对碳钢表面的缓蚀作用, 并从微观上对二者的缓蚀机理进行探讨. XPS测试结果显示, 由C, N元素的1s特征峰产生的化学位移及其积分峰面积表明TTC, TPT分子在金属表面产生了有效抑制腐蚀的保护层; 由椭圆偏振原位测试并结合动电位极化曲线测试,考察了TTC, TPT分子对金属表面腐蚀反应的抑制程度, 并得到了相位差等参量, 结果表明二者在金属表面形成了具有缓蚀作用的覆盖层.     

金属锌表面膜形成的椭圆偏振技术研究

介绍了近年作者课题组使用椭圆偏振技术研究金属锌表面氧化膜的形成,包括多晶锌表面自然氧化物薄膜的形成及其光学性能和电子结构、不同气氛自然氧化物膜的生长研究以及在碱性碳酸盐介质金属锌的电化学过程等方面的工作. 旨在通过原位和非原位椭圆偏振技术了解金属锌表面氧化物膜层的光、电性能以及膜层结构的改变和生长动力学,这对评估锌氧化层的总体性能有着重要意义.     

弱碱性介质中氯离子对铜电极腐蚀行为的影响

应用循环伏安法、X射线光电子能谱法、电化学阻抗谱法以及现场椭圆偏光法研究了在弱碱性介质中添加Cl－对铜电极腐蚀行为的影响.结果表明, Cl－的加入能加剧铜电极的腐蚀,使腐蚀电流以及现场椭圆偏振参数Δ的变化范围都增大1个数量级, Cl－对Cu2O的掺杂将使铜电极的表面膜变得疏松,膜的耐蚀性变差.椭圆偏光实验不仅与电化学和能谱实验的结果一致,而且还能定性地、清楚地分辨出铜电极腐蚀过程中Cu2O的生成、Cl－对Cu2O的掺杂、CuO的生成等不同阶段;同时,利用恰当的模型还能定量地确定各个阶段铜电极表面膜的组成、厚度的变化,从而为研究铜电极的腐蚀与防护机理提供更多有用信息.     

铅在铜上电沉积的原位椭圆偏振法

采用循环伏安法(CV)和原位椭圆偏振法(SE)研究铅在铜电极上的电沉积行为。 原位椭圆偏振参数Ψ和Δ值的变化率在CV图峰电位处同时出现极值。 通过建立单层膜模型描述“电极-溶液”界面的结构并对椭圆偏振光谱数据进行拟合得到铅沉积层厚度随电位的变化规律。 拟合结果显示,铅在铜电极上的电沉积有3个不同的沉积速率,-0.20～-0.35 V之间沉积速率为0.003 nm/mV,-0.35～-0.48 V之间沉积速率为0.025 nm/mV,-0.48～-0.60 V之间沉积速率为0.116 nm/mV,由此表明铅的电沉积分为3个不同阶段：欠电位沉积阶段、欠电位沉积向本体沉积的过渡阶段和本体沉积阶段。     

光谱椭圆法对Ni（OH）_2／NiOOH电化学性质的研究

用现场光谱椭圆偏振技术和电化学实验方法研究了Ｎｉ（ＯＨ）＿２／ＮｉＯＯＨ体系中的电化学反应．拟合椭圆偏振光谱的实验数据确定了阴、阳极过程中镍电极上表面膜的转化模型,结果表明：在镍表面上离子注入钻之后,表面膜转化模型基本保持不变,但Ｎｉ（ＯＨ）＿２／ＮｉＯＯＨ间电化学反应的性质受到明显影响．     

掠射椭圆偏振谱学方法数理模型的研究

掠射椭圆偏振谱学方法通过现场测量椭圆偏振参量Δ和Ψ能够反映电极过程的性质及变化规律.将电化学反应中的扩散层模型与掠射椭圆偏振实验体系相结合,提出了掠射椭圆偏振谱学方法的数理模型,对掠射椭圆偏振参量Δ和Ψ的物理化学意义做出了解释,认为电极表面附近的溶液扩散层对于椭圆偏振光既有相位延迟器的作用,又有振幅吸收器的作用；并应用一些实验结果,分析了电解液中电活性物质浓度和入射光束斑直径对掠射椭圆偏振参量的影响.     

掠射椭偏术对K4[Fe（CN）6]／K3[Fe（CN）6]电极反应的研究

提出掠射椭圆偏振测试技术的实验方案，应用该掠射式技术循环 安法研究了在镀有Ｉｎ２Ｏ３玻璃片上进行的Ｋ４「Ｆｅ（ＣＮ）６」／Ｋ３「Ｆｅ（ＣＮ）６」电极反应，结果证明：掠射椭圆偏嗥中在电化学反应过程中现场测定椭圆偏振参数及其变化规律，这些规律与所发生的表面电化学反应规律相对应，由此可以对电极体系进行研究，现场掠射椭圆偏振术还能用于分析表面扩散层的性质，弥补其它界面研究方法的缺陷。     

Quantitative chemical composition of thin films with infrared spectroscopic ellipsometry: application to hydrated oxide films on aluminium

A method to quantify the composition of thin films using infrared spectroscopic ellipsometry (IRSE), supplemented by visible spectroscopic ellipsometry (VISSE), is proposed. Because ellipsometry measures the thickness and optical constants of a surface layer simultaneously, the absorption coefficient of the film as a function of wavelength can be obtained. Using values of the absorption coefficients for the pure components of the film, the percentages (mol.% or wt.%) of each component in the film can be calculated. The method is demonstrated in a study of the hydration of oxide films on electropolished aluminium and the anodically formed barrier oxide film. The IRSE technique shows that hydration of the films by immersion in boiling water results in the conversion of aluminium oxide to pseudoboehmite. Copyright © 2003 John Wiley & Sons, Ltd.     

Total Internal Reflection Ellipsometry under SPR Conditions: In-Situ Monitoring of the Growth of Poly(N-isopropylacrylamide) (PNIPAAm) Brushes

Total internal reflection ellipsometry (TIRE) under surface plasmon resonance (SPR) conditions represents a powerful characterization technique combining the conveniences of spectroscopic ellipsometry with SPR. Besides the very high sensitivity to small changes in the optical constants (up to 10 times more sensitive than conventional ellipsometry), the possibility to investigate media of different optical densities or even opaque media makes this analytical method very convenient for different sensing applications. This article presents an example of application of TIRE under SPR conditions for the continuously in-situ monitoring of the growth of covalently tethered poly(N-isopropylacrylamide) (PNIPAAm) chains on a gold surface.     

Optical and physical properties of cobalt oxide films electrogenerated in bicarbonate aqueous media

For the first time, cobalt oxide films that are highly protective against localized corrosion and depicting a wide variety of bright and uniform colors due to light interference, have been successfully electrogenerated on polycrystalline cobalt disk electrodes under potentiostatic polarization in a mild aqueous bicarbonate medium. Open circuit potential measurements have shown the formation of a film with a bilayered structure, organized as a thin Co3O4 outer layer and a thick CoO inner layer. The existence of Co3O4 as a thin outer layer, previously postulated from galvanostatic reduction experiments, has been confirmed from XPS analysis. Raman spectroscopy, performed using a very low laser intensity, has shown that the films are mainly composed of CoO. The broadness of the Raman bands observed is associated to the amorphous character of the film, a result that has been confirmed by spectroscopic ellipsometry and X-ray diffraction analysis. Overall film thicknesses, well controlled by the anodization duration, were determined and correlated using mechanical (atomic force microscopy and profilometry) and spectroscopic (specular UV-vis-NIR reflectance and ellipsometry) techniques. Spectroscopic ellipsometry, using a simple amorphous dispersion model, has proved efficient for measuring thicknesses of films ranging from 31 to 290 nm with very low standard deviations. The real part of the complex refractive indices of these films, ranging from 1.8 to 2.2 (at lambda = 632.8 nm) depending on the anodization duration, is in good agreement with values reported in the literature for CoO. The film with the highest refractive index, and consequently the more densely packed structure, was obtained following a 30-minute anodization period.     

Comparative thickness measurements of SiO2/Si films for thicknesses less than 10 nm

We report on a comparative measurement of SiO₂/Si dielectric film thickness (t < 10 nm) using grazing‐incidence x‐ray photoelectron spectroscopy, neutron reflectometry and spectroscopic ellipsometry. Samples with nominal thicknesses of 3–7 nm were characterized by XPS with grazing‐incidence x‐rays at 1.8 keV, by cold neutron reflectometry (λ = 0.475 nm) and by spectroscopic ellipsometry over 1.5 eV < E < 6.0 eV. The results show good agreement between the ellipsometry and grazing‐incidence XPS, with slightly lower values for the neutron reflectometry. The role of surface contamination in each type of measurement is discussed. Published in 2004 by John Wiley & Sons, Ltd.     

Modelling the dielectric function of thin films measured by spectroscopic ellipsometry: determination of microstructure and density

The dielectric function of thin-film amorphous hydrogenated silicon (a-Si:H) deposited by the glow discharge and hot wire technique has been investigated by spectroscopic ellipsometry. An improved interpretation of the ellipsometric data taking into account the influence of hydrogen incorporation into the amorphous network enables to determine the film density and the void volume fraction of the material. Thus ellipsometry provides a convenient and contactless means of characterizing the structural properties of thin films. The film density varies considerably with substrate temperature and hydrogen content depending on the individual deposition technique. A reduction of film density is mainly caused by the formation of voids in the amorphous network. The influence of the substrate temperature on the growth of dense a-Si: H films is pointed out.     

Interface thickness of the incompatible polymer system PS/PnBMA as measured by neutron reflectometry and ellipsometry

The techniques of neutron reflectometry and spectroscopic ellipsometry are compared as methods to measure the interface width between immiscible polymers. The interface thickness of the incompatible polymer system of polystyrene (PS) and polyn-butyl methacrylate) (PnBMA) is determined by neutron reflectrometry to (6.4±0.2) nm and (8.6±0.2) nm at temperatures of 120 and 156°C, respectively. Some emphasis is put on the measurement of those values also by spectroscopic ellipsometry using the same materials. A special sample geometry is chosen for ellipsometric measurements to compensate for thickness changes of films during annealing, and the dispersions of PS and PnBMA films are determined. With respect to the determination of the interface widths, however, it turns out that in the available wavelength range of 280 to 700 nm spectroscopic ellipsometry is not sensitive enough to measure the thin interface width between PS and PnBMA films. Neutron reflectivity results obtained for PS/PnBMA are discussed with respect to the Flory-Huggins segment interaction parameter calculated within the approximations of meanfield theory.     

Experimental and theoretical contributions to the determination of optical properties of synthetic paramelaconite

Paramelaconite (Cu₄O₃) is a metastable copper oxide that can be barely synthesised in “pure” form. In this study, the reactive magnetron sputtering process was used to deposit Cu₄O₃ films on silicon and glass substrates. The deposited films were characterised by X-ray diffraction (XRD), UV-visible-NIR spectroscopy and spectroscopic ellipsometry. For the first time, the refractive index and the extinction coefficient of Cu₄O₃ were evaluated. The experimental values obtained from spectroscopic ellipsometry were compared to those calculated by a self-consistent approach using the Wien2k code. A very good agreement was found between the two sets of values.     

Layer‐by‐layer deposition of nitrilotris(methylene)triphosphonic acid and Zr(IV): an XPS,ToF‐SIMS,ellipsometry, and AFM study

Layer‐by‐layer assemblies consisting of alternating layers of nitrilotris(methylene)triphosphonic acid (NTMP), a polyfunctional corrosion inhibitor, and zirconium(IV) were prepared on alumina. In particular, a nine‐layer (NTMP/Zr(IV))₄NTMP stack could be constructed at room temperature, which showed a steady increase in film thickness throughout its growth by spectroscopic ellipsometry up to a final thickness of 1.79 ± 0.04 nm. At higher temperature (70 °C), even a two‐layer NTMP/Zr(IV) assembly could not be prepared because of etching of the alumina substrate by the heated Zr(IV) solution. XPS characterization of the layer‐by‐layer assembly showed a saw tooth pattern in the nitrogen, phosphorus, and zirconium signals, where the modest increases and decreases in these signals corresponded to the expected deposition and perhaps removal of NTMP and Zr(IV). Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) confirmed the attachment of the NTMP molecule to the surface through PO^?, PO₂^?, PO₃^?, and CN^? signals. Increasing attenuation of the Al signal from the substrate after deposition of each layer was observed by both XPS and ToF‐SIMS. Essentially complete etching of the alumina by the heated Zr(IV) solution was confirmed by spectroscopic ellipsometry, XPS, and ToF‐SIMS. Atomic force microscopy revealed that all the films were smooth with R_q roughness values less than 0.5 nm. Copyright © 2015 John Wiley & Sons, Ltd.