不同表面激光双向反射分布函数的实验研究

根据粗糙面电磁散射理论讨论了粗糙表面双向反射分布函数（ＢＲＤＦ）和单位面积激光雷达截面的关系。测量不同粗糙度金板、铝基、钢基和涂层样片在０．６３μｍ的双向反射分布函数。分析了高度起伏均方根δ，斜率起伏均方根ｓ，介电常数对双向反射分布函数的影响。最后，将部分粗糙样片的双向反射分布函数理论计算结果与实验数据比较，两者有良好的吻合。     

微晶硅薄膜的表面粗糙度及其生长机制的X射线掠角反射研究

采用等离子体增强化学气相沉积技术沉积一系列处于不同生长阶段的微晶硅薄膜.通过同步辐射X射线掠角反射技术研究微晶硅薄膜的表面粗糙度随时间等的演化，探讨微晶硅薄膜的生长动力学过程及其生长机制.研究结果表明，在衬底温度为200 ℃，电极间距为2 cm，沉积气压为6.66×1０² Pa，射频功率密度为0.22 W/cm²，氢稀释度分别为99%和98%的沉积条件下，在玻璃衬底上生长的微晶硅薄膜生长指数β分别为0.21±0.01和0.24±0.01.根据KPZ模型，微晶硅薄膜的生长机制为有限扩散生长. 关键词： X射线掠角反射 微晶硅薄膜 表面粗糙度 生长机制     

高精度表面粗糙度外差干涉仪信号处理系统的研制

针对用于磨床加工的光外差表面粗糙度在线干涉测量仪，文中介绍了整机的信号处理系统，着重讨论了两项关键技术。即宽动态范围测量信号的自动控制和高精度动态相位测量，系统的测量精度达２．６°（相当于３．２ｎｍ），允许测量中最大多普勒频移±２０ｋＨｚ（对应高度的变化率±８．７５×１０－３ｍ／ｓ），完全满足磨床加工中表面粗糙度在线测量的要求。现场测试证实了这一点，这对于精加工、超精加工表面粗糙度的在线质量控制、提高加工精度等非常重要。     

小尺度表面粗糙度与介质吸收对介质折射率测量的影响

将介质表面的小尺度粗糙度等效为覆盖在理想光滑表面上的多层等厚折射率渐变的薄膜,并通过特征矩阵计算多层等效膜模型的P光反射率与入射角的关系.将吸收介质的折射率虚部带入菲涅尔公式进行计算.运用COMSOL Mutiphysics软件对表面粗糙度和介质吸收进行建模和仿真计算.计算结果表明,小尺度表面粗糙度与介质吸收都会导致折射率测量产生误差.分别考虑以布儒斯特角和全反角作为折射率测量的手段,为了得到优于10-5的测量准确度,测量表面粗糙介质的折射率时,采用全反角进行判定;测量具有吸收效应的介质折射率时,采用布儒斯特角进行判定.     

Effect of inner-surface roughness of conical target on laser absorption and fast electron generation

The effect of inner-surface roughness of conical targets on the generation of fast electrons in the laser-cone interaction is investigated using particle-in-cell simulation. It is found that the surface roughness can reduce the fast-electron number （in the energy range E 〉 1 MeV） and energy, as compared to that from a cone with smooth inner wall. A scaling law for the laser reflectivity based on the vacuum-heating model is derived. Both theory and simulation indicate that laser reflection increases with the height-to-width ratio of the periodic inner surface structure and approaches that of a smooth cone as this ratio becomes zero.     

Effects of interface roughness on photoluminescence full width at half maximum in GaN/AIGaN quantum wells

Low temperature photoluminescence （PL） measurements have been performed for a set of GaN/AlxGal xN quantum wells （QWs）. The experimental results show that the optical full width at half maximum （FWHM） increases relatively rapidly with increasing A1 composition in the AlxGal xN barrier, and increases only slightly with increasing GaN well width. A model considering the interface roughness is used to interpret the experimental results. In the model, the FWHM＇s broadening caused by the interface roughness is calculated based on the triangle potential well approximation. We find that the calculated results accord with the experimental results well.     

Comparative study on corona-generated audible noise and radio noise of ac long-term operating conductors with two bundle types

The corona-generated audible noise (AN) and radio noise (RN) of the long-term operating conductors with two bundle types was investigated and compared based on a corona cage measurement system. The surface morphologies of eight conductors were measured and the average surface roughness (R_a) was calculated. With the raise of conductor bundles, the maximum electric field distortion level (β₄), the relative difference of ionization intensity (γ₄) between long-term operating conductors and new conductors decreased. Adding the number of sub-conductors turned out to be an effective method to improve AN and RN of long-term operating conductors in the contaminated areas.     

A System to Study the Effect of Particle Sizes in Aerosols on the Collection Efficiency in Impaction-Electrothermal Atomization Atomic Absorption Spectrometry

Abstract

The construction and use of a box system for a preliminary qualitative study of the effect of various dry aerosols, in the range 1 to 120 microns in size, on the collection efficiency of a single stage impactor connected to an electrothermal atomizer is described. Using a fixed flow rate of 5 L/min, jet diameter of 1 mm, and an uncoated graphite surface, particles < 50 microns were collected on the impaction surface and particles > 85 microns were not collected on the impaction surface. The jet-to-impaction surface was evaluated at a distance of 2 and 8 mm. It appeared that a jet-to-impaction distance of 8 mm gave improved collection efficiency of larger particles (> 50 microns).     

Qualitative and quantitative topographical surface investigation and solvent effects on internal surface of polypropylene tubes

An alternative way for plastic tubes surface analysis was presented, and the time course of the effects of solvent exposure was evaluated. Atomic force microscopy was used to qualitatively and quantitatively analyze internal tubes topography. Differences in nanoroughness parameters were shown as potential markers for quality control check to detect differences among brands and areas along each tube. Mass spectrometry analysis was carried out to evaluate the effects of some solvents after the intrinsic contact with the polymer. The obtained spectra did not allow the visualization of any leaching component, suggesting a low rate of some possible reaction or dissociative interaction caused by polymer and tested solvent interactions that were in concordance with principal component analysis. The use of these techniques as tools for quality control evaluation, or search for new support to biomolecules immobilization can be seen as important innovations and can be applied in several other investigative and developmental approaches. Copyright © 2011 John Wiley & Sons, Ltd.     

Single Potential Scan Methods for Nanoporous Gold Formation on Ultramicroelectrode Surfaces

Nanoporous gold (NPG) has been extensively investigated because of their applications. Here, we report a straightforward method for the preparation of NPG on micrometer-scale electrodes. Well-defined NPG structures were formed on Au surfaces by a single potential scan within 100 seconds. This method is applied to Au surfaces with small dimensions regardless of the electrode geometry, whereas it is not applicable to conventional millimeter-scale electrodes. The effects of electrode sizes and scan rates on NPG formation were systematically examined, and the amperometric glucose detection with 20-μL sample volumes using an ultramicroelectrode (UME) with NPG surfaces was demonstrated.