双光镊测量胶体微粒间相互作用势

分析了两个存在相互作用势的胶体微粒的布朗运动,讨论了通过微粒布朗运动的显微观测来测量胶体微粒间相互作用势的实验方法。将双光镊系统与同步斩光器相结合,建立了相应的测量系统。对1μm直径的聚苯乙烯球悬浮液中两个小球之间的静电相互作用势进行了实验研究。实验结果和DLVO(Derjagin-Landau-Verwey-Overbeek)理论符合较好,为DLVO理论提供了直接的微观实验依据。对决定实验精度和效率的一些实验因素,包括测量过程中光镊的开关切换时间、光镊打开和关闭的持续时间、样品离样品池底面高度和实验测量区间划分精度等进行了具体讨论。所建立的实验装置和方法可用于测量不同类型胶体粒子间的相互作用势,这为深入研究决定分散体系宏观性质的微观基础提供了一种有效的手段。     

基于多模光纤的动态光散射粒径测量研究

介绍了一种用多模光纤构造的动态光散射粒径测量实验系统,系统中没有对接收光纤的孔径角加任何限制措施.分别用单分散,多分散和不同浓度的标准聚苯乙烯乳胶球悬浮液检测了该系统的适用性.结果表明,该系统可准确地测量浓度(体积分数)达5%的聚苯乙烯乳胶球溶液中悬浮颗粒的粒径分布.     

倾斜底涂法制备聚苯乙烯胶体晶体及其光学特性研究

采用倾斜底涂法将单分散的聚苯乙烯胶体微球自组装生长成为胶体晶体,并用扫描电子显微镜和紫外-可见光分光光度计对其形貌和光学特性进行测量。结果表明,聚苯乙烯微球自组装为面心立方密堆积结构,胶体晶体的光子带隙位于可见光波段。分别对不同胶体颗粒的粒径、悬浮液的浓度、基片倾斜角度及环境温度等制备条件下生成的聚苯乙烯光子晶体样品逐一分类对比,分析了影响光子带隙宽度和深度的因素。     

聚苯乙烯-丙烯酸共聚物胶体纳米球核壳结构及其选择性溶解过程的表征

本文对采用自由基乳液聚合法制备的聚苯乙烯-丙烯酸(polystyrene-acrylic acid,PS-AA)共聚物胶体纳米球进行了微结构表征.发现原始合成的聚苯乙烯胶体球具有典型的核壳结构,磷钨酸(phosphotungstic acid,PTA)优先在核壳界面聚集.中心核主要由疏水性的苯乙烯组成,外壳主要由亲水性的丙烯酸组成.甲苯能对PS-AA胶体球进行原位选择性溶解.溶解过程中,胶体球发生溶胀破裂,中心聚苯乙烯初步溶解,孔结构经历了内径由小到大,孔边缘由粗糙不规则到光滑的变化过程.胶体球形成高分子孔结构,圆孔发生了一定程度的变形.     

磁性液体复合体的磁光效应

制备了含强磁性Ｆｅ３Ｏ４的纯磁性液体胶体和掺入聚苯乙烯小球的磁性液体复合胶体样品,系统测量了样品的双折射效应的线二向色性,并对测量结果进行了比较分析,认为磁性液体复合体非磁性小球的不同排列影响了它的磁光特性。     

垂直沉积法制备高质量胶体光子晶体

利用乳液聚合方法制备了粒径约为262 nm的单分散聚苯乙烯(PS)微球。通过控制溶剂蒸发温度和液体表面下降的速度,用垂直沉积法较快速地制备出了在较大范围呈现很好有序性的密排结构聚苯乙烯胶体光子晶体,其在626 nm波长处存在光子带隙。在扫描电子显微镜(SEM)下,观察到该胶体光子晶体是面心立方(fcc)密排结构。实验结果表明,对于粒径为262 nm的聚苯乙烯微球,在温度为55℃,质量分数为0.3%的情况下,当液体表面下降的速度约为每天3 mm时,可以得到高质量的胶体光子晶体。这种高质量的胶体光子晶体可以为利用模板技术制备具有完全带隙的有序孔结构提供较理想的模板。     

原子力显微镜在生物力测量中的应用

利用原子力显微镜(AFM)能够实现生物分子间作用力直接测量.本文讨论了利用AFM测量配体-受体之间的相互作用力、细胞粘着力、核酸双链和碱基对氢键间的作用力、运动蛋白之间的作用力、特殊化基团之间的作用力等方法.     

同步斩波法测量胶体粒子间相互作用势

本文介绍了CCD同步斩波装置与双光镊系统结合,构成的一套微小粒子相互作用势测量实验系统,并建立了相应的实验方法。利用该方法测量了1μm聚苯乙烯球悬浮液中两个小球间的相互作用势,其结果与经典DLVO理论相符。研究结果表明,我们所建立的实验系统和方法是行之有效的。并且测量方法具有较高的数据采集效率,该方法可望应用于粒子间不同类型相互作用势的测量。     

用于狭缝中的SAW应力传感器的设计与制作

为了对两曲面狭缝间的作用力进行监测,设计了一种基于声表面波（SAW）传感原理的无源无线应力传感器。首先,讨论了狭缝间作用力测量的传感技术方案,分析了弹性介质中力敏结构模型,进而确定了SAW谐振器的尺寸;其次,结合微机电系统(MEMS)加工工艺研究了该器件的制作工艺方案,包括SAW谐振器、支撑基底、传输线的制作。通过对SAW传感器设计与制作过程的探究,可为狭缝空间等极端环境中物理量的测量提供新的思路。     

激光烧蚀Ag纳米颗粒的制备和光学特性

利用Nd:YAG(523 nm)脉冲激光器对处于去离子水中的Ag片进行激光烧蚀,得到了Ag纳米颗粒与去离子水形成的Ag纳米胶体体系.由于制备这种Ag纳米胶体的是一种物理过程,所以具有较高的纯净性;由于这种Ag纳米胶体中无任何氧化剂或还原剂等外来杂质的干扰,具有非常好的纯净性和很好的表面增强Raman散射(SERS)活性.以对羟基苯甲酸(PHBA)作为探针分子,对这种增强基底的效果进行检测;并用量子化学中的理论模拟计算方法,对比研究了实验和理论的结果.     

Layer‐by‐Layer Growth of Multicomponent Colloidal Crystals Over Large Areas

Self‐assembly of different sized colloidal particles into multicomponent crystals results in novel material properties compared to the properties of the individual components alone. The formation of binary and, for the first time, ternary colloidal crystals through a simple and inexpensive confined‐area evaporation‐induced layer‐by‐layer (LBL) assembly method is reported. The proposed method produces high quality multicomponent colloidal crystal films over a broad range of particle size‐ratios and large surface areas (cm²) from silica/polystyrene colloidal suspensions of low concentration. By adjusting the size‐ratio and concentration of the colloidal particles, complex crystals of tunable stoichiometries are fabricated and their structural characteristics are further confirmed with reported crystal analogues. In addition, complex structures form as a result of the interplay of the template layer effect, the surface forces exerted by the meniscus of the drying liquid, the space filling principle, and entropic forces. Thus, this LBL approach is a versatile way to grow colloidal crystals with binary, ternary, or more complex structures.     

Optical demultiplexing in a planar waveguide with colloidal crystal

We report the first experimental demonstration of demultiplexing capabilities of a 2-D waveguide grating consisting of a monolayer colloidal crystal deposited on a top of a planar waveguide. Self-assembled periodical structure with hexagonal symmetry is formed by crystallization of polystyrene colloidal particles. The experiments are performed in the 1550-nm wavelength region     

垂直沉积法在GaAs衬底上制备有序SiO2胶体晶体

报道了一种利用直径为286nm的单分散SiO2胶体颗粒制备胶体晶体的方法。乙醇悬浮中的SiO2颗粒通过毛细作用力在垂直插入其中的GaAs衬底表面自组装成胶体晶体。扫描电子显微镜（SEM）和紫外-可见分光光度计对胶体晶体的形貌和光学特性进行了表征。结果显示,所得到的胶体晶体膜具有较好的三维有序结构。分析了退火对样品光子带隙的影响。     

Rapid Fabrication of Two‐ and Three‐Dimensional Colloidal Crystal Films via Confined Convective Assembly

We have developed a self‐assembly method for fabricating well‐ordered two‐dimensional (2D) and three‐dimensional (3D) colloidal crystal films. With a minute amount of a polystyrene colloidal suspension and without any special equipment, the proposed method can be used to rapidly deposit high‐quality colloidal crystal films over a large surface area. By controlling the lift‐up rate of the substrate, we modulate the meniscus thinning rate, which determines whether the colloidal particles are assembled into two or three dimensions. The proposed method can be used to fabricate not only monolayered colloidal crystals with colloidal particles of various sizes, but also multilayered colloidal crystals. In addition, the method enables us to fabricate binary colloidal crystals by consecutively depositing large and small particles.     

Fabrication of Periodic Nanostructure Assemblies by Interfacial Energy Driven Colloidal Lithography

A novel interfacial energy driven colloidal lithography technique to fabricate periodic patterns from solution‐phase is presented and the feasibility and versatility of the technique is demonstrated by fabricating periodically arranged ZnO nanowire ensembles on Si substrates. The pattern fabrication method exploits different interfaces formed by sol–gel derived ZnO seed solution on a hydrophobic Si surface covered by a monolayer of colloidal silica spheres. While the hydrophobic Si surface prevents wetting by the seed solution, the wedge shaped regions surrounding the contact point between the colloidal particles and the Si substrate trap the solution due to interfacial forces. This technique allows fabrication of uniform 2D micropatterns of ZnO seed particles on the Si substrate. A hydrothermal technique is then used to grow well‐defined periodic assemblies of ZnO nanowires. Tunability is demonstrated in the dimensions of the patterns by using silica spheres with different diameters. The experimental data show that the periodic ZnO nanowire assembly suppresses the total reflectivity of bare Si by more than a factor of 2 in the wavelength range 400–1300 nm. Finite‐difference time‐domain simulations of the wavelength‐dependent reflectivity show good qualitative agreement with the experiments. The demonstrated method is also applicable for other materials synthesized by solution chemistry.     

High Quality Factor Metallodielectric Hybrid Plasmonic–Photonic Crystals

A 2D polystyrene colloidal crystal self‐assembled on a flat gold surface supports multiple photonic and plasmonic propagating resonance modes. For both classes of modes, the quality factors can exceed 100, higher than the quality factor of surface plasmons (SP) at a polymer–gold interface. The spatial energy distribution of those resonance modes are carefully studied by measuring the optical response of the hybrid plasmonic–photonic crystal after coating with dielectric materials under different coating profiles. Computer simulations with results closely matching those of experiments provide a clear picture of the field distribution of each resonance mode. For the SP modes, there is strong confinement of electromagnetic energy near the metal surface, while for optical modes, the field is confined inside the spherical particles, far away from the metal. Coating of dielectric material on the crystal results in a large shift in optical features. A surface sensor based on the hybrid plasmonic–photonic crystal is proposed, and it is shown to have atomic layer sensitivity. An example of ethanol vapor sensing based on physisorption of ethanol onto the sensor surface is demonstrated.