共查询到20条相似文献,搜索用时 15 毫秒
1.
动态光散射技术的角度依赖性 总被引:2,自引:0,他引:2
与单角度动态光散射技术相比,多角度动态光散射(MDLS)颗粒测量技术能够提高颗粒粒度分布的测量准确性。但在MDLS技术中,测量角度的选择常常与被测颗粒体系的分布有关。对100nm、500nm的单峰模拟分布和300nm与600nm混合的双峰模拟分布的颗粒体系,分别在1、3、6、9个散射角条件下进行了测量。颗粒粒度反演结果表明,随着散射角个数的增大,颗粒粒度分布更趋于真实的颗粒粒度分布。对数量比为5:1的100nm与503nm双峰分布的聚苯乙烯颗粒,分别在1、3、5、10个散射角条件下进行了测量,实测结果表明采用单角度测量只能得到单峰分布,3个及更多散射角可得到双峰分布,并且双峰的数量比随散射角数量的增加逐渐趋近真实的数量比。因此,MDLS颗粒测量技术能够改善颗粒粒度分布的测量结果,但这种改善程度会随散射角的增多逐渐降低。由于散射角个数的增多会增加散射角的校准噪声和光强相关函数的测量噪声,因而会导致在有些情况下颗粒粒度分布的测量结果反而变差。 相似文献
2.
3.
小粒子动态光散射信号的计算机模拟及分析 总被引:6,自引:0,他引:6
用计算机模拟了小粒子(0.001μm~1μm)的动态光散射信号,并对其进行了分析,同时运用分形几何学(FractalGeometry)的理论和概念,对信号的时间复杂性进行了分数维(FractalDimension)的计算,得出了它与粒子尺寸之间的关系。 相似文献
4.
5.
动态光散射图像法测量纳米颗粒粒度研究 总被引:4,自引:0,他引:4
提出了一种基于动态光散射原理的图像法测量纳米颗粒粒径的新方法,采用面阵CCD数以万计的像素同时并行测量处于布朗运动的纳米颗粒空间分布的动态散射光信号,对测得的信号进行数据处理,得到了纳米颗粒粒径。对27、79、482、948nm 4种不同粒径的纳米标准颗粒进行了实验研究,针对面阵CCD拍摄帧率远低于光电倍增管测量频率的特点,采用质量分数为55%高粘度甘油水溶液作为分散介质,在CCD拍摄帧率为8290frame/s时,27nm颗粒的测量误差从以水为分散介质时的15.1%降至1.9%。与目前动态光散射纳米颗粒测量方法相比,该方法大幅度减少了测量时间,仅为现有方法的1%以下,并可大幅度简化测量装置。 相似文献
6.
Determination of Soot Particle Size in a Premixed Flame: a Static and Dynamic Light Scattering Study
Gert Kroner Heribert Fuchs Reinhard Tatschl Otto Glatter 《Particle & Particle Systems Characterization》2003,20(2):111-123
In this contribution we report upon our static and dynamic light scattering experiments to characterize soot particles in flames. We studied sooting laminar premixed flame with acetylene as fuel mixed with air as oxidizer. The air equivalence ratio of the combustion was larger than one. We used a Kaskan type burner with circular geometry and a stabilizing flow of nitrogen around the flame. We focused on the determination of the size of the soot particles in the center of the flame as a function of height above burner. In addition we investigated the influence of the mixing ratio of the gases on the size of the particles. Our results show that static light scattering is better suited than dynamic light scattering for a fast and reliable characterization of soot particles in flames. The latter needs detailed a priori information about the flame to allow the unique determination of sizes from the diffusion measurements. The soot particles grow monotonously with height above burner and with decreasing air equivalence ratio. The aggregates have a fractal dimension lower than two. 相似文献
7.
光复散射对消光法粒径测量的影响:复散射模型与数值模拟 总被引:13,自引:3,他引:13
复散射效应在光散射颗粒测量中不仅重要.且尚未得到很好解决。采用蒙特卡罗方法,对不同的光波长,颗粒浓度以及收接器条件下的光复散射进行了数值模拟.数值算法程序经与四通量模型进行对比验证,数值结果与单散射条件的郎伯-比尔模型进行比较.进而讨论了复散射效应对消光法颗粒粒径测量影响。表明复散射对消光法颗粒测量的影响不仅取决于颗粒系自身的浓度.而且接收器的几何尺寸和接收位置起着非常重要的作用,减小颗粒介质层厚度和减小光接收器接收面积.增大接收距离以及减小接收角都能减小复散射效应对消光法粒径测量的影响。 相似文献
8.
米氏理论的近似及在粒度测量中的应用 总被引:7,自引:0,他引:7
将夫琅禾费衍射理论与几何散射 (包括折射和反射 )相结合 ,给出平行光入射下圆形颗粒在前向大角度范围内的散射光强分布近似算法。由于考虑了衍射、折射和反射相互间的干涉效应和颗粒对光的吸收性 ,对于正常或非正常衍射状态下无因次参量α≥ 40的耗散颗粒 ,在前向 0°~ 60°散射之内 ,该方法对散射光强计算结果与米氏理论结果是吻合的。由于计算速度比米氏理论快 ,有效角度范围比夫琅禾费衍射理论宽 ,因而适合于大颗粒的前向光强计算。将这一计算方法应用到大角度采光时的激光粒度测量实验中 ,收到了良好的效果 相似文献
9.
Ya jing Wang Jin Shen Gang Zheng Wei Liu Xin jun Zhu 《Particle & Particle Systems Characterization》2012,29(2):93-103
In order to conveniently obtain dynamic light scattering (DLS) signal, a simulation method of DLS signal is proposed in this paper. This method regards the light intensity fluctuation of DLS as a stationary random process. According to autocorrelation function (ACF) of DLS signal, the stationary random process of DLS can be generated by auto‐regressive (AR) model. Signal simulations of several kinds of distribution particles and comparison of simulations and experiment prove that AR model can be used for DLS signal simulation. Moreover, by analyzing effect of simulation parameters on simulation precision, we obtained the relationship between simulation parameters and simulation precision. Finally, application of simulation signal verifies the effectiveness and convenience of this simulation method. 相似文献
10.
Dynamic light scattering (DLS) techniques for studying sizes and shapes of nanoparticles in liquids are reviewed. In photon correlation spectroscopy (PCS), the time fluctuations in the intensity of light scattered by the particle dispersion are monitored. For dilute dispersions of spherical nanoparticles, the decay rate of the time autocorrelation function of these intensity fluctuations is used to directly measure the particle translational diffusion coefficient, which is in turn related to the particle hydrodynamic radius. For a spherical particle, the hydrodynamic radius is essentially the same as the geometric particle radius (including any possible solvation layers). PCS is one of the most commonly used methods for measuring radii of submicron size particles in liquid dispersions. Depolarized Fabry-Perot interferometry (FPI) is a less common dynamic light scattering technique that is applicable to optically anisotropic nanoparticles. In FPI the frequency broadening of laser light scattered by the particles is analyzed. This broadening is proportional to the particle rotational diffusion coefficient, which is in turn related to the particle dimensions. The translational diffusion coefficient measured by PCS and the rotational diffusion coefficient measured by depolarized FPI may be combined to obtain the dimensions of non-spherical particles. DLS studies of liquid dispersions of nanometer-sized oligonucleotides in a water-based buffer are used as examples. 相似文献
11.
12.
分段自相关动态光散射法测量亚微米粒度 总被引:5,自引:0,他引:5
介绍了动态光散射法测量微粒尺度的原理,通过对相关函数相对的分析,提出了分段自相关的方法,该方法解决了高速,大数据量采集的困难,又不显著影响相关函数的精度,给出了实验装置及实验结果,测量结果与标准样品的标称值相符。 相似文献
13.
利用虚拟仪器开发软件LabVIEW设计了基于光子计数原理的动态光散射纳米颗粒测量系统.采用光电倍增管(H6240-01)作为检测器件以及光子计数板(M9003)对单光子信号计数,利用LabVIEW作为软件平台,并用brookhaven的标准纳米颗粒进行了实验,取得了较好的测量效果. 相似文献
14.
为了获取超细颗粒动态散射光模拟信号, 在分析超细颗粒动态散射光信号特性的基础上, 通过建立动态光散射随机过程的自回归(AR)模型, 利用Levison-Durbin递推算法确定模型参数, 并给出了单峰、双峰分布颗粒信号模拟的模型阶数确定方法, 从而提出了一种基于AR模型的态光散射信号模拟方法。分别对50 nm, 300 nm, 1000 nm, 50 nm与1000 nm, 100 nm与500 nm, 300 nm与1000 nm的单峰、双峰分布颗粒在模型阶数分别为1, 1, 1, 57, 28, 40时进行了模拟, 得到的模拟信号的光强自相关函数与理论值吻合, 用累积法对单峰分布颗粒反演和双指数法对双峰分布颗粒反演, 相对误差分别小于0.58%和3.7%, 因此, 单峰分布颗粒信号模拟需一阶模型, 双峰分布颗粒信号模拟粒径不同所需阶数不同。 相似文献
15.
The Mie Scattering Imaging method (MSI) gathers out‐of‐focus images of dispersed spherical particles present in a laser light sheet and extracts the individual particle diameter from these images. The general idea of the method has been around for more than a decade and a number of papers has dealt with it over recent years. Our work focuses on small particle sizes from 20 μm down to 2 μm, a range which has not been tackled so far although it is of great importance in particle systems. We present an optical set‐up with a special arrangement of camera lenses that allows to work in this range. An evaluation algorithm based on correlation of the experimental optical information with theoretical Mie scattering was found to give the most accurate results for particle sizing. Besides accuracy measurements on solid spheres the versatility of the method is demonstrated by an example of transient droplet growth between 2–7 μm. 相似文献
16.
17.
18.
Michael Kaszuba Malcolm T. Connah Fraser K. McNeil‐Watson Ulf Nobbmann 《Particle & Particle Systems Characterization》2007,24(3):159-162
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. 相似文献
19.
20.
基于偏振双向反射分布函数,从理论上推导了瑞利缺陷粒子分别位于光学表面上方和基底内部的散射场,研究了光学表面瑞利缺陷粒子的方位诊断问题.通过对不同波长下冗余缺陷粒子位于不同方位时双向反射分布函数pp项的分析与讨论实现对缺陷位置的初步判断.结果表明,SiO2瑞利缺陷粒子位于裸基底上方时,双向反射分布函数pp项受波长影响的敏感程度远大于位于SiO2涂覆上方时,可以通过测量缺陷粒子对波长变化的敏感程度判断缺陷粒子的大致方位;当缺陷粒子在Si基底下方时,方位角的凹痕出现在85°到90°之间,当缺陷粒子在SiO2涂层下方时,方位角的凹痕出现在70°左右,因此,可以根据方位角凹痕位置的不同实现对缺陷粒子方位的进一步诊断. 相似文献