也谈光散射增强

增强是上世纪七十年代,在(非弹性)光散射中发现的重要现象之一。在过去几十年中,人们锲而不舍投入了大量的时间和经费,时至今日,已有各种机制来说明或解释它,但仍不尽人意。十余年来,超高增强(g是增强因子~10~(14-15))的报导更是将它推向一新的境地,原有的想法遇到了莫大的障碍和挑战,必须用新的思想(格林函数的极或散射截面)考虑、处理这类问题。本文除了讲述非弹性光散射光强的基础知识之外,还给出了过往未能理解和阐述的内容,如分形、极化、纳米、准相位匹配和单分子层界面等结构的增强,为该领域的工作提出了新的方向和路径。     

应用低相干动态光散射法测量悬浮液中的颗粒粒径分布

利用低相干动态光散射法测量不同浓度悬浮液中的颗粒粒径分布。由低相干光源和迈克尔逊干涉仪,结合传统的动态光散射技术组成低相干动态光散射装置,通过检测单次背散射光的能谱分布,利用CONTIN算法得到不同浓度悬浮液中颗粒的粒径分布。结果表明,对于1%～10%体积浓度范围内的单分散悬浮液羊品测量得到的颗粒粒径精确度在4%以内。     

利用低相干光纤动态光散射法测量浓悬浮液中多分散颗粒粒径分布

本文针对高浓度散射介质,用低相干光纤动态光散射技术测量浓悬浮液中多分散颗粒系的粒径及其粒径分布。利用迭代CONTIN算法对实验数据进行反演运算,得到多分散颗粒系的粒径分布结果。结果表明,浓悬浮液中多分散颗粒系的峰值粒径测量值与给定的两种标准粒径值相吻合,其误差在4%之内,粒径分布曲线中各散射颗粒所反映的散射体光强分布与根据Mie散射计算得到的理论值相吻合。实验结果证明低相干光纤动态光散射实验系统能准确测量浓悬浮液中多分散颗粒粒径及粒径分布。     

The Estimation of Multiple Light Scattering in Turbid Colloidal Suspensions using a 2-Probe Detector

This paper describes a detector for the direct measurement of multiple scattering in moderately turbid colloidal suspensions. The detector uses two optical fibers aligned so that one of the fibers measures the total signal (single and multiple scattering) and the other measures multiple scattering only. We report the results of preliminary investigations, and show how such a detector can be used to aid both static and dynamic light scattering investigations. In the former case we show how this information can be used to correct for low level multiple scattering. The utility and limitations of the technique are discussed.     

Numerical Analysis on Enhanced Backscatterings of Light Based on Rayleigh-Debye Scattering Theory

Enhanced backscatterings from the disordered dense media are investigated by means of the Monte Carlo simulation. On the basis of the Rayleigh-Debye scattering theory, numerical simulations demonstrate the dependences of the peak, width and spatial anisotropy of enhanced intensity distributions on the size of scattering particles. Discussions are made by decomposing the backscattering intensity to the contributions with different scattering orders. As a result, it is shown that the particle-size dependence of the peak and width is described by the probability density function of the scattering order and the mean free pathlength. It is also shown that the spatial anisotropy of the intensity peak is described by the depolarization at each scattering event and the extinction in propagation within the random media.     

Light Scattering by Human Blood Plasma

Transmission of laser radiation in human blood plasma diluted with physiological solution is studied. Comparison with scattering in pure physiological solution is made. General and individual optical characteristics of blood plasma from different patients are established.     

Light Scattering by Clusters: the Al-Term Method

This paper concerns the theoretical improvement of the discrete dipole approximation (DDA) to provide scattering properties of clusters of spherical monomers. The first scattering coefficient (al-term) in Mie theory is introduced to determine the dipole polarizability used in the DDA. In the al-term method, a spherical monomer in the cluster is replaced by a single dipole. The accuracy of this method is tested to calculate extinction and scattering cross sections by a single sphere, two-touching spheres and three collinear touching spheres. It is found that when each monomer is replaced by a dipole the al-term method is superior to the different types of DDA, e.g., the Lattice Dispersion Relation (LDR), at least for the target with the volume equivalent size parameter X, 0.2≦X≦2. This method also allows treatment of a relatively large sub-volume element which is replaced by a dipole, i.e. the size parameter of the monomer X_m∼1.5. Furthermore, a great reduction in memory requirement and computing time are achieved, e.g. for two touching spheres the al-term method requires only 6% of the total memory requirement and 0.008% of the total computing time for N=8448 with the LDR.Part of this work was done when the author was in the Institute of Physics, GKSS Research Center, Postfach 1160, D-21494 Geesthacht, Germany     

共振光散射法测定三聚氰胺

应用共振散射光谱技术建立三聚氰胺检测新方法。三聚氰胺可使甲醇体系在567nm处的共振散射光明显增强。在优化实验条件下,体系的ΔI值与三聚氰胺的浓度在0.7—16.0mg/L之间具有良好的线性关系,线性方程为ΔIRLS=40.53C(mg/L)-2.64,r=0.9993;检出限为0.21mg/L;样品加标回收率为92.6%—102.3%。方法灵敏,操作简便,分析成本低,用于奶粉中三聚氰胺的测定,结果满意。     

Anisotropy of Light Scattering by Foamed Liquids

Optics and Spectroscopy - Optical transport parameters (transport propagation length of radiation and scattering length) have been experimentally studied in samples of a foamed liquid for a...     

十六烷基三甲基溴化铵敏化孔雀石绿-脱氧核糖核酸的共振光散射增强法测定脱氧核糖核酸

在碱性条件下 ,脱氧核糖核酸 (DNA)对孔雀石绿的共振光散射有增强作用 ,加入十六烷基三甲基溴化铵 (CTMAB)进一步敏化该体系。共振光散射增强的程度与DNA浓度呈良好的线性关系 ,据此建立了测定DNA的共振光散射增强分析方法。在实验条件下 ,最大散射波长 36 4nm处 ,测定小牛胸腺DNA(ctDNA)和鱼精子DNA(fsDNA)的线性范围皆为 0～ 1 5 μg·mL-1,检出限分别为 0 0 5和 0 0 3μg·mL-1。该方法简单、快速、灵敏度高 ,已成功应用于合成样品中DNA含量的测定。     

Detection Theory of Polydispersities by Dynamic Light Scattering

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微米级高聚物包埋型金属铁复合粒子的球磨法制备及其磁流变效应

采用球磨法,能成功地直接从高聚物与金属铁的混合研磨中,获得微米级由聚苯乙烯和 甲基丙烯酸甲酯等高聚物包埋型金属羰基铁复合粒子。详细讨论制备条件包括不同高聚物比例、球磨时间对复合粒子形貌和粒径的影响及其复合粒子的热稳定性,还简要研究了由这些粒子组成的浓有机悬浮溶液的磁流变效应及其粒子的沉降稳定性。     

偏振同步光散射和同步光散射光谱区分与同时测定奎宁和奎尼丁对映异构体

在酸性缓冲溶液中,阴离子表面活性剂十二烷基苯磺酸钠SDBS能与金鸡纳类生物碱药物体系中一对对映异构体QN和QD作用产生增强的同步光散射(synchronous light scattering,SLS)信号,本文首先利用偏振同步光散射(polarized synchronous light scattering)信号,建立了同步光散射偏振度(P)区分QN和QD这对对映异构体,同时利用同步散射光谱和双标准曲线计量分析法对2种金鸡纳类生物碱药物进行同时测定,并将该方法应用于尿样中QN和QD的同时测定,结果令人满意。     

Settling Behavior Characterization of Submicron Particles in Dilute and Concentrated Suspensions

In separation processes, the knowledge of particle size and density arc often not enough to describe the settling behaviour in a concentrated suspension. Therefore, a direct method for the characterization of the settling behavior of submicron particles in concentrated suspensions is introduced in a centrifugal field by a manometric sedimentation analysis. By means of this cumulative method in a homogeneous suspension, the analyses of both the interfacial settling rate and the settling rate of the particles within the concentrated suspension are possible. This permits a differential examination of settling processes in a broad concentration range. First, the influence of the solid concentration on the settling rate at the interface and within a monodisperse suspension with a range from 0.01 to 30 vol.% is represented. The relationship between the increase in settling rate through particles settling in a cluster and a concentration decrease in the suspension is also represented. Consideration of the possibilities of the analysis of polydisperse suspensions demonstrates the field of applications for this method.     

表面增强拉曼散射探测细胞酶的活性

本文以5-溴-4-氯-3-吲哚基-β-D-吡喃半乳糖苷为底物,探测细胞结构中β-半乳糖苷酶的活性。作为β-半乳糖苷酶的底物,5-溴-4-氯-3-吲哚基-β-D-吡喃半乳糖苷在细胞β-半乳糖苷酶酶解作用下,形成靛蓝染料衍生物,在贵金属表面具有较强的表面增强拉曼散射。这种通过表面增强拉曼光谱探测细胞酶活性的方法,与高速拉曼线扫描相结合,可以快速地评估细胞种群的酶活性。     

LBO晶体的光散射研究

ＬＢＯ晶体的光散射研究王越，蒋毅坚，刘玉龙（北京工业大学应用物理系北京１０００２２）（中科院物理研究所北京１０００８０）ＳｔｕｄｙｏｎｏｎＬＢＯＣｒｙｓｔａｌｂｙＬｉｇｈｔＳｃａｔｔｅｒｉｎｇ￥Ｙ．Ｗａｎｇ￣１；Ｙ．Ｊ．Ｊｉａｎｇ￣１ａｎｄＹ，Ｌ．Ｌ...     

A Spheroidal Model of Light Scattering by Nonspherical Particles

Optics and Spectroscopy - We have constructed a spheroidal model to solve the problem of light scattering by nonspherical particles. The semiaxes of the model spheroid are determined based on the...     

共振光散射法测定盐酸羟胺

研究了在醋酸缓冲介质中,盐酸羟胺还原Cu2+定量所形成CuSCN的共振散射光谱.确定了散射光强度与溶液中盐酸羟胺浓度的关系.提出了共振散射法测定盐酸羟胺的新方法.方法的检出限为0.04μg/mL,线性范围为0.04-0.80μg/mL.方法用于工业品盐酸羟胺的测定,结果满意.