4-(2-吡啶偶氮)-间苯二酚的共振散射光谱研究

研究了4-(2-吡啶偶氮)-间苯二酚(PAR)水溶液的共振散射光谱的形成机理与影响因素。在弱酸性溶液中,PAR可产生很强的共振光散射, 散射光谱形状与吸收光谱有关。溶液酸度影响PAR的电离平衡和存在状态,因而影响散射光谱。在pH 3.1～6.2之间,PAR为不带电荷的中性分子,可在疏水力的作用下结合形成分子聚合体,从而导致共振光散射增强。光偏振实验表明PAR的散射光为完全偏振光。在一定实验条件下,光散射强度与PAR浓度之间存在线性关系。     

(非弹性)光散射概念

(非弹性)光散射现象的发现、研究和应用已有八十余年的历史,所涉及的过程,特征量,及由此关系到的物理概念、各种图像特别的繁多;想要统一、规范它们似乎难以达到。但对已成熟的,如:光散射(包括非弹性、弹性);选择定则;虚态;散射截面;相干性;‘和’、‘差’频;波数、波矢、偏振和模式等概念还是可以给出完好的解说和认识的。该文给出了上述概念的物理内容,尽可能的给出相应的图像,以便获得明白的结论。     

基于Mie散射理论的铌酸锂晶粒散射特性

基于Mie散射理论,对铌酸锂晶粒光散射特性进行了理论分析与数值计算,得到了散射强度分布、偏振度与散射角、散射强度与粒子尺寸参数,以及光学截面与粒子半径的关系。研究表明:前向散射占优势,并随粒子半径的增大而增强;当粒子半径为0.1 μm 左右,散射截面和吸收截面达到最大值。     

A Review of Elastic Light Scattering Theories

Mie scattering is an important tool for diagnosing microparticles or aerosol particles in technical or natural environments. Mie theory is restricted to spherical, homogeneous, isotropic and non-magnetic particles in a non-absorbing medium. However, as microparticles are hardly ever spherical or homogeneous, there is much interest in more advanced scattering theories. During recent decades, scattering methods for non-spherical and non-homogeneous particles have been developed and even some computer codes are readily available. Extension of Mie theory covers coated spheres, stratified spheres and clustered spheres. For homogeneous non-spherical particles such as spheroids, ellipsoids and finite cylinders, surface discretization methods have been developed. Scattering by inhomogeneous particles may be computed by volume discretization methods.     

散射光场中的光学涡旋

散射光场中的光学涡旋叶茂，王鹏业，戴建华，张洪钧（四川大学物理系成都６１００６４）（中国科学院物理研究所北京１０００８０）ＯｐｔｉｃａｌＶｏｒｔｉｃｅｓｉｎＡＴｈｅｒｍａｌＲａｙｌｅｉｇｈＳｃａｔｔｅｒｉｎｇＬｉｇｈｔＦｉｅｌｄ￥ＭａｏＹｅ；ｐｅｎｇ...     

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...     

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     

Time-Resolved Small-Angle Light Scattering Apparatus

We have successfully implemented a time-resolved small-angle light scattering apparatus with spatial averaging by means of conical lens or software processing. Averaging allows a significant reduction of measurement times and makes this technique suitable for the study of systems with very long times-scales, from 25 Hz to many hours. We report light scattering experiments on the dissolution of polymer blends and light reflection measurement from polymer composites as examples of applications.     

槲皮素的共振光散射光谱研究

研究了槲皮素(Qu)的共振光散射光谱和吸收光谱,结果表明,pH在3.30～6.50范围内,Qu的共振光散射信号很强且稳定,当pH＞6.50时,共振光散射强度随pH的增大而迅速减小。在pH 4.00的B-R缓冲溶液中,在λ=497 nm处,共振光散射强度在一定浓度范围内与Qu的浓度成线性关系,线性范围为0.0～3.0×10-4 mol·L-1, 相关系数r＞0.999, 检测限为3.1×10-7 mol·L-1。同时运用量子化学计算方法对Qu分子内、分子间氢键进行了计算,理论计算表明: Qu共振光信号增强的原因是Qu分子通过4-4’分子间氢键聚合形成了超分子聚合体, 这一结论和实验得到的光谱数据完全吻合。     

Light Scattering by Small Multilayer Particles: A Generalized Separation of Variables Method

A Rayleigh approximation is constructed for light scattering by small multilayer axisymmetric particles, in which their polarizability is determined by the generalized separation of variables method (SVM). In this method, scalar potentials, the gradients of which yield the electric-field strengths, are represented as expansions in spherical harmonics of the Laplace equation. Unknown coefficients of expansions are determined from the boundary conditions, which are reduced to infinite systems of linear algebraic equations (ISLAEs), since the separation of variables is incomplete. The T matrix of the electrostatic problem, principal element T₁₁ of which is proportional to the particle polarizability, is determined. The necessary condition for the ISLAEs solvability for the SVM coincides with the condition of the correct application of the extended boundary conditions method (EBCM). However, numerical calculations in which finite-dimensional (i.e., reduced) systems are solved, yield different results in ranges of variation of parameters that are close to the boundary of the range of applicability. An analysis of the numerical calculations of the scattering and absorption cross sections for two-layer confocal spheroids, an exact solution for which can be obtained using spheroidal harmonics, shows that the SVM is preferable to the EBCM. It turned out that the proposed method yields workable results in a wider range of variation of parameters. Even outside the range of applicability, in which it should be regarded as a certain approximate solution, its use in a number of cases is quite acceptable. Additional calculations for three-layer nonconfocal spheroids, as well as for three-layer similar pseudospheroids and Pascal’s snails, which can be obtained from spheroids as a result of the inversion with respect to the coordinate origin and one of the foci, respectively, confirm these inferences. We note that, for certain values of the parameters, the shapes of the latter particles are nonconvex.     

Cylindrical Fibre Orientation Analysis by Light Scattering. Part 2: Experimental Aspects

An experimental set-up has been designed to record maps of intensity distribution for two orthogonal polarizations allowing the retrieval of average information along the optical path. A wide variety of the signatures of different samples is given to characterize the spatial orientation of a cloud of infinite cylinders by using a light scattering method. The information contained in the images is discussed and compared with numerical predictions.     

Cylindrical Fibre Orientation Analysis by Light Scattering. Part 1: Numerical Aspects

The scattering of a finite beam by an ensemble of infinite cylinders, with a spatial orientation function of the depth, is simulated by using a Monte Carlo type code, including multiple scattering effects. The properties of the scattered light collected by detectors, such as the spatial distribution of intensities, are predicted, taking into account the polarization dependence.     

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.     

动态光散射技术的角度依赖性

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。     

分形凝聚粒子的光散射特性研究

粒子的形状和凝聚对光散射特性有着很大的影响.基于分形生长的受限扩散(DLA)模型,模拟了凝聚粒子的三维空间分形结构,并采用回转半径法计算了凝聚粒子的分形维数.利用离散偶极子近似(DDA)方法研究了纳米石墨凝聚粒子的光散射特性,对于原始粒子数不同的凝聚粒子及分形结构不同的凝聚粒子,数值计算了散射强度和偏振度随散射角的分布...     

煤烟聚集粒子的光散射特性研究(英文)

基于分形理论,用计算机模拟了由球形基本粒子构成的煤烟聚集粒子。利用离散偶极子近似方法(Discrete Dipole Approximation)研究了煤烟聚集粒子的散射特性,讨论了分形煤烟聚集粒子的散射强度随煤烟聚集粒子的分形结构、大小、相对折射率及入射波波长变化情况。     

动态光散射中的多普勒效应

动态光散射中的多普勒效应郭凤岐１）刘秋霞２）（武汉工业大学数理系材料学院武汉４３００７０）ＤｏｐｐｌｅｒＥｆｅｃｔｉｎＤｙｎａｍｉｃＬｉｇｈｔＳｃａｔｅｒｉｎｇＧｕｏＦｅｎｇｑｉ，ＬｉｕＱｉｕｘｉａ（Ｄｅｐｔ．ｏｆＭａｔｈ．ａｎｄＰｈｙｓ．，Ｗｕｈａ...     

罗丹明B的共振散射光谱研究

研究了罗丹明B(RhB)的共振光散射的特性与机理。在 pH =- 0 38至 pH 4 10的酸性溶液中 ,共振光散射信号随pH值增大而增强 ,近中性时散射强度达到最大。散射强度随波长的变化不符合瑞利散射定律。RhB的荧光激发光谱与发射光谱有部分重叠 ,共振散射峰处于荧光激发峰和荧光发射峰之间。在三维荧光等高线光谱图中 ,瑞利散射线与荧光等高线相交。在光偏振实验中 ,测得共振散射光的偏振度P≈ 0 1。上述实验结果揭示RhB的共振散射光主要是共振荧光。共振光散射信号随 pH值增大而增强的机理是RhB酸碱平衡移动导致荧光型体的形成。RhB的共振散射峰位于吸收曲线轮廓之中 ,共振光散射受光吸收的影响 ,因此 ,散射光强度与浓度之间不是严格的线性关系。