表面光散射法液体黏度和表面张力实验系统研制

基于气液界面表面波理论和表面光散射原理,本文研制了表面光散射液体黏度和表面张力实验系统,实验系统包括,实验光路、耐高压样品池控温系统和数据采集和处理系统组成。实验系统压力测试范围为0~10 MPa,温度测试范围为283~400 K,温度波动度小于±10 mK/10 h。采用光频外差的方法提取液体表面波信息,并通过数值求解表面波色散方程获得液体黏度和表面张力。利用参考物质甲苯检验了实验系统,本文获得的黏度值与参考方程的最大偏差为1.3%,平均偏差为0.52%;表面张力值与拟合值的最大偏差0.39%,平均偏差为0.23%。通过不确定度分析,本文搭建的系统测量黏度和表面张力的不确定度为别为2%和1%。     

近临界区表面光散射法乙醇界面性质的实验研究

针对高温及近临界区流体界面性质测量难题,本文研究了表面光散射法在该温度区间流体表面张力和黏度的高精度测量方法。获取了饱和状态下乙醇在温度范围为303 K~T_c内的表面张力和黏度,并利用实验数据分别拟合了对应的van der Waals方程和含临界项的温度倒数多项式方程,在全温度范围内实验值与方程的偏差均在1.5%之内。同时分析了表面光散射法测量流体表面张力和黏度的测量扩展不确定度,当对比温度T_r=T/T_c0.9时,表面张力和黏度的测量不确定度分别为1%和2% (k=2);当对比温度0.90 T_r 0.99时,测量不确定度范围分别为1%~7%和2%~3%(k=2)。     

低散射角度下表面光散射法仪器加宽效应理论修正与流体表面性质测量

表面光散射法流体界面性质传感要求既快速又准确，故需采用较小的散射角度来获取更强的散射光信号以提升测量速度，同时又需修正低散射角条件下引入的仪器加宽效应以确保测量准确性。理论上，在假定入射激光为高斯光束的条件下，发展了频域内修正低散射角条件下引入的仪器加宽效应的方法，并开发了利用参考数据获得表面光散射实验系统的仪器加宽常数算法与多波数条件下表面波的频谱修正和拟合算法。实验上，利用低黏度的制冷剂R1336mzz(Z)和高黏度的十四酸乙酯分别检验了理论的准确性。所提方法可将表面光散射法测量流体黏度和界面张力的单点测量时间从原来的10～20 min缩短至2～5 min，并保持相同的测量精度。     

基于表面光散射法的聚乙二醇水溶液表面张力实验研究

基于表面波散射原理,本文研制了表面光散射法表面张力实验系统。利用标准参考物质纯水和乙醇对实验系统的可靠性进行了检验,并标定了散射角度。结果表明:新系统测量的两种物质的表面张力实验结果与标准数据的偏差为0.1mN·m~(-1),散射角度约为0.2°。利用新的表面光散射法表面张力实验系统,对质量分数为4%~16%的PEG1000、PEG2000、PEG4000、PEG6000、PEG8000水溶液的表面张力进行了实验研究,结果表明:PEG水溶液的表面张力随着PEG质量分数的增大有减小趋势,且PEG水溶液的表面张力与PEG本身的聚合度无关;PEG4000和PEG6000水溶液具有较大的表面张力,可以作为潜在的诱导蛋白质结晶的沉淀剂。     

高精度气液相平衡实验系统的建立和实验测定

本文搭建了循环法气液相平衡实验系统,介绍了该实验系统的组成,设计了循环法实验系统的实验流程.本实验系统的温度、压力和摩尔组分浓度的测量不确定度分别为5 mK,600 Pa和0.001.使用该实验系统测定了R125和R290纯净物饱和蒸气压,并进一步开展了R125+R290体系的气液相平衡实验研究,给出了该体系在3个温度下的等温气液相平衡实验数据,采用状态方程法相平衡模型对实验数据进行了关联分析,并与文献值进行了比较,结果表明本文实验数据具有较高精度,也说明了实验系统的可靠性.     

表面光散射法正十六烷高温热物理性质研究

为拓展高温下流体黏度和表面张力的测量,改进了原有的表面光散射实验系统,将实验的温度区间拓展至570K,改进后的系统在整个温区内测量黏度和表面张力的扩展不确定度分别为2%和1%(k=2)。利用新的实验系统研究了正十六烷在353~547 K温度范围内的黏度和表面张力,并利用实验数据分别拟合了温度倒数多项式和van der Waals方程,在全温度范围内实验值与方程的偏差均在1%之内。在较宽的温度范围内获得的正十六烷的高精度黏度和表面张力数据和方程,可以作为参考数据和方程,用于相关仪器的标定和检验。     

动态光散射法热/质扩散系数同时测量方法研究

流体工质的热、质扩散系数是表征其传热和传质的重要迁移性质,往往需要采用不同设备测量获得。为探索可同时测量热、质扩散系数的动态光散射方法,研究了采样时间、入射角、黏度、折射率偏差及路易斯数Le等因素对测量可靠性及精度的影响。利用二元混合流体正己烷/正癸烷、正己烷/正十六烷体系进行验证,结果表明：当采样时间为弛豫时间的1.5～3倍且入射角度为8°～12°时,具有较低黏度、较高折射率偏差（>4%）的体系且Le值为10～80时,可以同时可靠地获取流体热、质扩散系数,且测量不确定度低于5%;与已有方法对比,热、质扩散系数的偏差分别为4.00%和3.56%,证明了该测量方法和系统的可靠性。     

差压波动对孔板气液两相流测量的影响

差压波动是气液两相流动的固有物理现象,应用该波动可以测量干度和气液总流量。为了研究差压波动对孔板气液两相流测量的影响,本文在压力0.7~1.0 MPa,气相流量200~400 kg/h,干度0.4~1范围内测量了不同流动工况下的差压波动过程。实验结果表明差压平均值和差压标准差可以反映两相流流动参数的变化,但差压标准差重复性较差;实验范围内差压标准差的重复性变化范围为士0.3%~士18.5%;对于低含液率两相流(LNF0.3%),差压平均值的波动会"掩盖"液相流量变化造成的差压值变化;误差传递会导致总流量的预测误差大于干度的预测误差;对于高干度两相流(x0.5),误差传递会导致液相流量预测误差被放大。     

气液界面微观结构研究的一种实验新方法

许多物理、化学和生物过程发生于气液界面,且受到局域微观结构的深远影响. 不同于液体的体相,分子取向是界面处微观结构突出的不对称特征之一. 本文综述了电子碰撞时间延迟质谱方法和近期取得的进展. 利用这个崭新的方法,不仅可以侦测得到利用小角度X射线或中子散射以及振动和频光谱方法获得的界面微观结构,同时也提供了一种研究气液界面处电子驱动化学反应的实验方案.     

气液界面微观结构研究的一种实验新方法（英文）

许多物理、化学和生物过程发生于气液界面,且受到局域微观结构的深远影响.不同于液体的体相,分子取向是界面处微观结构突出的不对称特征之一.本文综述了电子碰撞时间延迟质谱方法和近期取得的进展.利用这个崭新的方法,不仅可以侦测得到利用小角度X射线或中子散射以及振动和频光谱方法获得的界面微观结构,同时也提供了一种研究气液界面处电子驱动化学反应的实验方案.     

R32/PAG润滑油体系的黏度和质扩散系数实验研究

本文采用光散射法对R32/PAG润滑油混合体系的动力黏度和质扩散系数进行了实验研究,温度范围从293.15~353.15 K,压力范围从0.09~1.26 MPa,共计获得16个数据点。R32/PAG体系的表面波散射特性属于过阻尼区,当温度一定时,R32/PAG混合物的黏度随着R32所占比例的升高而减小。本文黏度、质扩散系数实验数据与所获得模型的平均绝对偏差分别为1.17%、0.15%,可用于R32/PAG制冷系统的优化设计。     

基于增强拉曼散射的光子-原子双模压缩态的实现

拉曼散射过程中利用原子系综中初始制备的自旋激发(原子相干性),以及注入与原子系综中初始制备的自旋激发相关联的种子光场都可以极大的提高光场频率转换的效率,实现增强拉曼散射.本文理论上计算了增强拉曼散射过程中原子-光场量子界面的正交分量的量子起伏,得到了相干性导致的增强拉曼散射,只能在一定的范围内稍微提高初始光子-原子的压缩度;而关联增强拉曼散射,能够制备很强的光子-原子间的双模压缩.这样强压缩度的光子-原子量子界面,对于利用光场和原子系统实现量子精密测量研究有着非常重要的应用.     

Resolving Concentrated Particle Size Mixtures Using Dynamic Light Scattering

Dynamic light scattering (DLS) is a technique used for measuring the size of molecules and particles undergoing Brownian motion by observing time‐dependent fluctuations in the intensity of scattered light. The measurement of samples using conventional DLS instrumentation is limited to low concentrations due to the onset of a phenomenon called multiple scattering. The problems of multiple scattering have been addressed in a light scattering instrument incorporating non‐ invasive backscatter optics (NIBS). This novel optic arrangement maximizes the detection of scattered light while maintaining signal quality and allows for measurements of turbid samples. This paper discusses the ability of backscatter detection to accurately determine particle sizes at 1 %w/v sample concentrations and demonstrates the correct resolution of different size populations using a series of latex standard mixtures with known volume ratios. The concentration of 1 %w/v is much higher than can be measured on conventional dynamic light scattering instruments.     

Light scattering from colloids

This paper presents a review of light scattering results on static and dynamic properties of ordered colloidal suspensions of charged polystyrene particles and fractal colloidal aggregates. Our studies on static structure factor,S(Q), of ordered monodisperse colloidal suspensions and binary mixtures of particles with different particle diameters, measured by angle-resolved Rayleigh scattering will be discussed. This will include determination of bulk modulus using gravitational compression and observation of colloidal glass (inferred from splitting of the second peak inS(Q)). Dynamic light scattering, with real time analysis of scattered intensity fluctuations, is used to get information about Brownian dynamics of the particles. Recent advances in the field of light scattering from colloidal aggregates which show fractal geometry will also be discussed.     

Peculiarities of critical light opalescence in a spatially limited multicomponent system

The light scattering by a spatially limited liquid multicomponent system near its critical state is investigated. A radially symmetric system is considered. The pair correlation functions of the density fluctuations of the components, on the basis of which the intensity of the single scattering of light is analyzed, are calculated for this system. It is shown that the light scattering in spatially limited multicomponent systems can be studied within the framework of approaches used for single-component and binary mixtures.     

Dynamic light scattering of a concentrated multicomponent spherical particle solution

The“measured”dunamic structure function of highly concentrated and smallspherical colloidal system with a narrow distribution of particle sizes can be expressed in termsof the sum of two independent modes due to collective diffusion and polydispersity fluctuationsrespectively.The“measured”static structure functions S~M(K) is derived,and applied to cal-culate the polydispersity distribution.The relationship between the moments of the gammaparticle size distribution and the moments determined by a dynamic light scattering measure-ment is developed for the case when the particles are small and spherical.     

Critical surface scattering of x-rays at grazing angles

We study the cross-section for x-ray scattering under conditions of total reflection on surfaces of semi-infinite systems undergoing a continuous phase transition in the bulk. Because of their finite penetration, totally reflected x-rays probe the local surface order parameter and its critical fluctuations. The angular and temperature dependence of the scattered intensity gives experimental access to several critical surface exponents.We consider in particular order-disorder transitions in binary alloys and discuss some requirements on angular and temperature resolution which have to be met by experiments.This work was supported by the Bundesministerium für Forschung und Technologie     

Three-dimensional Monte Carlo simulation of bulk fin field effect transistor

In this paper,we investigate the performance of the bulk fin field effect transistor(FinFET) through a threedimensional(3D) full band Monte Carlo simulator with quantum correction.Several scattering mechanisms,such as the acoustic and optical phonon scattering,the ionized impurity scattering,the impact ionization scattering and the surface roughness scattering are considered in our simulator.The effects of the substrate bias and the surface roughness scattering near the Si/SiO2 interface on the performance of bulk FinFET are mainly discussed in our work.Our results show that the on-current of bulk FinFET is sensitive to the surface roughness and that we can reduce the substrate leakage current by modulating the substrate bias voltage.     

Dynamic light scattering at the ice water interface during freezing

The 488 nm radiation of an argon laser is scattered quasi-elastically at the [0001]-face (basal plane) of a growing ice crystal. The scattering plane is the basal plane. The Rayleigh-linewidth is proportional to the square of the scattering vector. One measures about 2 krad/s at a scattering angle of 90°. The linewidth does not depend on the growth rate. Scattering is only observed once a critical growth rate ν_crit = 1,5 μ m?s has been exceeded. Then the scattering intensity depends linearly on the growth rate in the range between 0,03 μ m?s and 2,5 μ m?s. Once the surface is molten scattering vanishes and does not reappear until the growth rate has again exceeded the threshold ν_crit. The coherence properties of the scattered light indicate that the thickness of the scattering layer is less than 6 μ m. The observations are interpreted in terms of a fluctuating interface. The decay time of the fluctuations has been calculated. Satisfactory agreement with the observed Rayleigh linewidth is obtained.