La纳米自组装膜的制备及摩擦学性能研究

采用乙二胺四乙酸(EDTA)分子自组装技术在硅基材料表面制备了稀土La复合纳米膜,利用浓缩体系全功能稳定性分析仪研究了自组装改性剂制备温度对氢氧化镧胶粒稳定性的影响,通过X-射线荧光光谱仪(XRF)研究了自组装改性剂溶液pH值对复合纳米膜中引入La量的影响,利用AFM研究了EDTA/La摩尔比及组装时间对复合纳米膜形貌的影响,利用AFM研究了在硅基材料表面自组装复合稀土纳米润滑膜前后的摩擦磨损性能.结果表明,在玻璃基片表面成功地组装上了稀土La纳米薄膜;相对于原构件,La纳米膜表面粘附力较小,摩擦因数亦较低,呈现出良好的润滑效果;其摩擦稳定性和耐磨性都有很大程度上的提高.     

磁头表面含氟硅烷自组装膜的制备和摩擦学性能

利用分子自组装技术,在磁头表面制备1H,1H,2H,2H-全氟葵烷基三乙氧基硅烷(FTE)自组装膜。应用时间飞行二次离子质谱仪(TOF-SIMS)、原子力显微镜(AFM)和接触角测量仪对FTE自组装膜进行表征。通过O lympus磁头磁盘界面可靠性测试系统对FTE自组装膜的摩擦学性能进行研究。实验结果表明磁头表面可制备膜厚1.2 nm、接触角值110.6°、表面粗糙度0.198 nm的FTE单层自组装膜。FTE单层自组装膜能够降低磁头起停过程的粘着力、增强磁头的摩擦性能,具有良好的耐磨性能。     

氨基表面组装薄膜的构筑及其微观摩擦学特性

以二乙烯三胺基丙基三甲氧基硅烷(TA)作为分子底层,采用两步组装的方法在单晶硅基底表面制备一系列相同结构不同分子链长的自组装双层薄膜。利用椭圆偏光测厚仪、接触角测定仪、原子力显微镜(AFM)等对薄膜的形成及微观摩擦力进行表征。研究结果表明,低表面能的疏水性末端基团有利于降低薄膜的摩擦力和摩擦因数;组装分子碳链长度的增加有助于形成有序性强和致密度高的组装薄膜,从而减小薄膜表面的摩擦力和摩擦因数。     

C60自组装单分子膜的制备及其磨擦特性

利用胺基与C60分子的加成反应,在3-胺基丙基-三乙氧基硅烷(APS)的自组装单分子膜(SAMs)表面上成功的制备了与基底化学键结合的C60-SAMs.其表面水接触角约为76°,膜厚约为1.15 nm,AFM形貌像显示其表面光滑、均匀,基本不含缺陷.摩擦学结果表明,APS自组装单分子膜由于其分子链短,膜的有序性差,表面颗粒聚集物及"针孔"等缺陷多,而不具有润滑作用.当在其上形成C60单分子层膜后,表现出优异的摩擦学性能,摩擦系数约为0.09～0.13,在给定实验条件下抗磨损寿命大于10 000次,有望作为微型机械的边界润滑材料使用.     

基于微探针加工技术的分子自组装过程实验研究

运用原子力显微镜纳米加工系统,在工件表面加工出了多种复杂微结构。并以此为基底,研究了基底形貌对嵌段共聚物自组装纳米微结构的调控作用。将自上而下的基于AFM微探针的纳米机械技术与自下而上的分子自组装技术相结合,实现了对有序纳米微结构的调控。     

硫醇自组装膜在金表面吸附行为的AFM力曲线研究

本文用原子力显微镜（AFM）对硫醇自组装金电极表面随机取点测得力曲线，并对力曲线粘附力数据进行统计分析，结果表明随自组装液中硫醇浓度改变，粘附力特征呈现出关联性的变化。力曲线所揭示的自组装膜吸附行为的变化规律和传统电化学方法交流阻抗（EIS）测试所得结论一致，表明AFM力曲线技术可应用于自组膜吸附行为的研究。     

基于机械—化学方法硅表面芳香烃重氮盐单层膜的制备

基于金刚石刀具建立能在溶液中加工微小结构的微加工系统,在一端为硝基的四氟化硼芳烃重氮盐溶液(NO2 C6H4N2BF4)中用该系统切削硅片,利用机械与化学结合的方法使得芳香烃分子和切削过的硅片之间以共价键连接,实现硅表面的“成形并功能化”的一步完成,为纳米尺度功能化结构的构筑提供一定的试验基础。用扫描电子显微镜(Scanning electronic microscopy,SEM)表征不同切削力下的微结构表面形貌图,为下一步在溶液中“成形并功能化”硅表面提供好的基底。用X射线光电子能谱(X-ray photoelectron spectroscopy,XPS )和原子力显微镜(Atomic force microscopy,AFM)分别研究组装时间和切削速度对切削处生成自组装单层膜(Self-assembly monolayer,SAMs)质量的影响,总结出本试验条件下切削力为20 mN,组装时间为12 h左右,切削速度为500 nm/s的时候组装膜表面质量较好。并用AFM对自组装膜的纳米摩擦性能进行检测,证明组装前后硅基底表面的化学组成发生了变化,组装后SAMs表面的摩擦力较大。     

原子力显微镜在蛋白质研究中的应用

AFM对于蛋白质的研究是一个极好的工具,它可以进行表面成像、分析蛋白质的大小和体积、测量蛋白质空间结构,表征蛋白质的结构与功能、了解分子间的相互作用等等。本文主要从AFM样品制备及其在蛋白质研究中的应用等几个方面进行了系统地阐述。     

铜表面硅烷自组装膜的制备及其摩擦学特性的研究

利用分子自组装技术在纯铜表面制备十七氟葵基硅烷单分子膜,用X射线光电子能谱对薄膜的表面结构进行表征,分析自组装膜的成膜机制,并利用UMT-3摩擦磨损试验机评价薄膜的摩擦磨损性能。接触角测试表明,该薄膜具有疏水性,其对水的接触角达117°。摩擦磨损实验结果表明,铜片表面沉积硅烷单分子膜可以大幅度降低铜基片的摩擦因数,使铜基片表面的摩擦因数由无膜时的0.8降至0.23,且在低负荷下具有很好的耐磨性。     

自组装技术制备稀土Y润滑薄膜的研究

结合自组装技术在羟基化处理的Si表面成功制备了稀土Y薄膜。利用SEM,AFM,XPS对其结构和形貌进行表征,在UMT-2摩擦磨损试验机上考察了稀土Y薄膜的摩擦磨损性能,并探讨了该薄膜的摩擦润滑机制。结果表明,利用该方法制备的稀土薄膜致密、均匀,由排布紧凑的小颗粒组成,具有良好的减摩耐磨特性。     

原子力显微镜在聚合物研究中的应用

原子力显微镜以其分辨率高、样品无需特殊制备、实验可在大气环境中进行等优点而广泛应用于聚合物研究之中,弥补扫描隧道显微镜不能观测非导电样品的缺憾。近年来,其应用已由对聚合物表面几何形貌的观测发展到纳米级结构和表面性能的研究领域。在介绍原子力显微镜工作原理的基础上,简要回顾其在聚合物研究方面的若干新应用,并对其应用前景作展望。     

AFM characterization of biomolecules in physiological environment by an advanced nanofabricated probe

Many relevant questions in biology and medicine require both topography and chemical information with high spatial resolution. Several biological events that occur at the nanometer scale level need to be investigated in physiological conditions. In this regard Atomic Force Microscopy (AFM) is one of the most powerful tools for label‐free nanoscale characterization of biological samples in liquid environment. Recently, the coupling of Raman spectroscopy to scanning probe microscopies has opened new perspectives on this subject; however, the coupling of quality AFM spectroscopy with Raman spectroscopy in the same probe is not trivial. In this work we report about the AFM capabilities of an advanced high‐resolution probe that has been previously nanofabricated by our group for coupling with Raman spectroscopy applications. We investigate its use for liquid AFM measurements on biological model samples like lipid bilayers, amyloid fibrils, and titin proteins. We demonstrate topography resolution down to nanometer level, force measurement and stable imaging capability. We also discuss about its potential as nanoscale chemical probe in liquid phase. Microsc. Res. Tech., 2012. © 2012 Wiley Periodicals, Inc.     

基于快速原子力显微镜的正弦驱动信号设计

随着人们对微观世界的探知需求,原子力显微镜（AFM）的扫描速度与扫描范围愈发限制其在纳米级领域的应用。各种提高AFM扫描速度的手段应运而生。通过分析扫描速度过快对图像的影响以及对正弦驱动可行性的考察,利用Filed Programmable Gate Array（FPGA）为核心,结合基于PCI04控制系统的AFM的快速扫描的特点,设计正弦波驱动信号。设计中采用查表的方式以及嵌入式nios Ⅱ处理器,实现正弦信号的输出与串口通讯。从而将AFM扫描探针的驱动信号由传统的三角波变为正弦波以提高其扫描速度。     

A New AFM Nanotribology Method Using a T-Shape Cantilever with an Off-Axis Tip for Friction Coefficient Measurement with Minimized Abbé Error

A new AFM (atomic force microscopy) nanotribology method using a T-shape cantilever with an off-axis tip (Nat Nanotechnol 2:507–514, 2007) has been developed for measuring friction coefficient at nanometer scale. In this method, signals due to both bending and twisting of the T-shape AFM cantilever are detected simultaneously. For a T-shape AFM cantilever, the bending is caused by the normal load and the twisting is caused by both the normal and the lateral loads. The twisting generated by the normal load is calibrated in advance. Consequently, the twisting only due to the lateral load can be decoupled from the total lateral voltage signal. And the friction coefficient can be finally determined based on a conversion relationship between the normal and lateral voltage signals of the AFM photodetector. A practical procedure for minimizing Abbé error in friction coefficient measurement has also been introduced. The proposed new method is simple and accurate, and requires the least operation for friction coefficient measurement at nanometer scale.     

A novel probe–sample separation estimation scheme for atomic force microscopy

This paper presents a novel estimation scheme to calculate the probe–sample separation in atomic force microscopy (AFM). The AFM is capable of measuring the sample topography by using a probe to interact with the sample. The interaction is dominated by the atomic force which is dependent on the probe–sample separation and sample properties. The key to successful AFM applications is accurate sensing and regulation of the probe–sample separation in nanometer scale. Our proposed scheme provides an accurate estimate of the probe–sample separation based on the information of the main sinusoidal and its harmonics. The estimation is shown to have a good performance even when noise is present.     

基于原子力显微镜的纳米加工研究

以原子力显微镜(AFM)作为加工工具对单晶硅进行了基于金刚石针尖的纳米加工试验,运用不同的方法对纳米加工区域的特性、材料在不同垂直载荷下的去除机理及切屑形成特征进行了系统的研究和分析,提出了一种在纳米尺度下研究加工机理的新方法。在此基础上,应用有限元法对AFM纳米加工中存在于金刚石针尖和被加工材料之间的接触作用机制进行了计算仿真。     

Lateral Displacement of an AFM Tip Observed by In-Situ TEM/AFM Combined Microscopy: The Effect of the Friction in AFM

When the lateral displacement of an AFM tip due to friction is comparable to or larger than the scan size, for example during atomic-scale friction measurement, the interpretation of the friction image is different from the situation where the scan size is much larger than the lateral displacement of the tip and the image is a simple direct mapping of the friction value. This is because, due to the lateral displacement of the tip, the tip is not at the position where the scan indicates, as can be clearly observed by an in-situ TEM/AFM combined microscopy and atomic-scale friction analysis. This lateral displacement of the tip at the nanometer scale affects the shape of the force-distance curve. We discuss the effect of the tip lateral displacement in AFM data and its normal load dependence.     

Imaging of silkworm meiotic chromosome by atomic force microscopy

Although structural information of mitotic chromosomes has been accumulated, little information is available for meiotic chromosome structures. Here, we applied atomic force microscopy (AFM) to investigate the ultrastructures of the silkworm, Bombyx mori, meiotic pachytene chromosome in its native state with nanometer scale resolution. Two levels of DNA folding were observed on the meiotic chromosome surface, 50-70 nm granules, which were considered to be 30 nm chromatin fibers, and spherical protrusions of 400-600 nm, which were considered to be chromomeres and arranged on the surface of the chromosome parallel to the chromosome longitudinal axis. These observations suggested that AFM study is an excellent approach for obtaining information concerning the silkworm pachytene chromosome higher order structure.     

配置程控样品台的原子力显微镜重定位成像方法

原子力显微镜(Atomic Force Microscopy)已成为在纳米尺度对样品进行观察和操纵的重要工具。基于原子力显微镜观测的重定位技术提供一种微观区域内对样品处理前后原位对比观测的方法。本文利用坐标实时显示的程控高精度样品台系统,联合使用表面双标记定位法,建立一种新的重定位方法,方便、高效地实现样品重定位AFM成像。     

Carbon nanotubes: a promising standard for quantitative evaluation of AFM tip apex geometry

The direct contact between tip and sample in atomic force microscopy (AFM) leads to demand for a quantitative knowledge of the AFM tip apex geometry in high-resolution AFM imaging and many other types of AFM applications like force measurements and surface roughness measurements. Given, the AFM tip apex may change continuously during measurements due to wear or during storage due to oxidation, it is very desirable to develop an easy and quick way for quantitative evaluation of AFM tip radius when necessary. In this study, we present an efficient method based on Zenhausern model (Scanning 14 (1992) 212) by measuring single-wall carbon nanotubes deposited on a flat substrate to reach this goal. Experimental results show the method can be used for routine quantitative evaluation of AFM tip apex geometry for tips with effective radii down to the nanometer scale.