内混合气溶胶粒子体系有效吸收系数的计算

分析了以黑碳和水组成的内混合强吸收气溶胶粒子体系有效吸收系数随时间变化的规律,并讨论了不同波长、不同半径比等对有效吸收系数的影响。结果表明：波长越短,内混合气溶胶粒子体系有效吸收系数越大,在1~100 s内随时间增大的速度也越快,1~100 s内的增幅比100~1000 s内的大,最大增幅达到132.65%;不同的内外半径比对内混合气溶胶粒子体系的有效吸收系数有较大影响,内外半径比越大,有效吸收系数越大,在1~100 s有效吸收系数增加速度越快,1~100 s内增幅较大,最大增幅达到138.66%。     

非球形大气粒子对任意波束的电磁散射特性

研究大气中变形球状的气象粒子对电磁波以及激光的散射特性,采用广义米氏(Mie)理论,精确地求解在任意波束中大气粒子的散射强度,数值计算激光束腰位置对散射强度分布的影响,分析彩虹强度和散射角与变形球状粒子偏心率的关系,研究随着长短轴比例增加,彩虹强度峰值的偏移。计算结果表明雨滴在下降过程中,它在各个方向的光散射强度逐步减弱,即随着雨滴偏心率的增大,散射强度减少,彩虹角变大。对于激光入射,当粒子距离波束中心位置越远,粒子的散射就越弱,并且随尺寸参量增加,后向散射振荡的频率要大于前向散射,当束腰位置矢径的大小增加时,后向散射和前向散射强度均变小。     

微粒光散射理论与测试技术研究

本文全面系统的论述了不同粒度段光散射理论与粒度分布测试技术 ;报道了基于MIE散射理论的亚微米粒度分布测试理论与技术的研究成果 ,提出了基于夫朗和费衍射理论的修正公式和密集颗粒粒度的测试方法。     

基于双粒子耦合的单层介质柱阵列对电磁波的调控

基于Mie散射理论和多重散射理论探讨了亚波长介质柱阵列对电磁波的调控. 研究结果表明: 当在全反射的单层介质柱阵列中引入一个空位缺陷时会产生12%的透射; 如果在入射一侧再引入一合适的介质柱时, 其透射率可增加至36%, 为空位缺陷时的3倍; 当在出射一侧对称位置处引入另一完全相同的介质柱时, 可以调制透射电磁波的模式, 虽然总的透射率没有增加,但向前散射的电磁波能量明显增强. 采用这种双粒子耦合体系, 在金属柱的表面等离激元共振频率附近也可以实现类似的效果. 这些体系结构简单、易于在实验上实现, 这对于太赫兹甚至光频段的光子集成线路中的元件设计和光束调控很有意义.     

A Comprehensive Brownian Dynamics‐Based Forward Model for Analytical (Ultra)Centrifugation

In this study, it is demonstrated how Brownian dynamics (BD) simulations can be used as a comprehensive forward model for analytical ultracentrifugation (AUC) and analytical centrifugation experiments. BD simulations are a versatile alternative to the numerical solution of Lamm's equation. Time dependent concentration profiles can be accurately predicted by means of the BD simulations even for colloidal systems with multiple species. It is shown that in combination with Mie's theory for light scattering, BD simulations can be extended to generate data mimicking a multiwavelength detector for AUC. The forward model can be utilized as a comprehensive tool for developing and testing sophisticated data analyzing tools that can enhance the capabilities of using centrifugation‐based techniques for characterizing nanoparticles. The model is validated using common analysis tools developed for the evaluation of sedimentation velocity data generated by a single wavelength extinction detector. The accuracy of the code is also proved using the recently developed and highly versatile High Dynamic Range‐MULTIwavelength FITting tool for accurately predicting particle size distributions via gravitational sweep experiments performed in AUCs equipped with multiwavelength detectors.     

红磷烟幕中红外光谱和红外消光性能研究

在中型烟幕试验柜中测试了红磷烟幕的红外光谱和粒度分布,分析了红磷烟幕在7.4μm~13.8μm波段的红外透过率和消光系数.测试了红磷烟幕对10.6μm激光的质量消光系数.根据M ie理论计算了红磷烟幕粒子对该波段红外的散射、吸收和消光效率因子.结果表明,在中等湿度条件下红磷烟幕对8.2μm~11.0μm红外和入射功率为1.0W的10.6μm激光的质量消光系数分别为0.424m2/g和0.396m2/g.红磷烟幕在成烟后10m in~30m in时间内粒度分布在0.5μm~3μm.平均粒度较小的红磷烟幕对中红外辐射的消光主要是吸收作用,随着烟幕粒度增加,散射作用和消光效果逐渐加强.     

用简化Mie理论及K—K关系求微粒复折射率的透射法

用简化的Ｍｉｅ散射理及Ｋｒａｍｅｒｓ－Ｋｒｏｎｉｇ关系式，从单频透射比光谱反演微粒的复折射率，用较大粒径的碳黑微粒作了模拟计算，结果表明本方法计算比较简单，比现有方法提高了精度，扩大了波长及粒径范围。最后利用红外分光光度计测出的透射比光谱确定煤粒的复折射率。     

Mie scattering calculation by FDTD employing a modified Debye model for Gold material

The parameters calculation for the modified Debye model in the electromagnetic finite difference time domain (FDTD) method is discussed. Validation for the selected parameters is done comparing the FDTD results with the Mie analytical solutions of a gold nanometer sphere under an optical plane wave incidence. Good agreement with an average relative error 6.7% has been demonstrated as to total electrical field amplitudes on the surface of the gold sphere. It indicates FDTD could be adopted in the optical region for a material even with a negative real relative permittivity particularly as metals.     

求非均匀体系微粒光学常数的透射法

结合精确Ｍｉｅ散射理论及光学常数色散Ｋ－Ｋ关系，利用具有某一粒径分布的稀相，非均匀微粒弥散系的透射比光谱，反演微粒的光学常数。研究了反问题方法的多值性，并讨论了该方法的适用范围，分析了粒径分布函数偏差，非均匀弥散系的均匀似及透射比误差及对反演结果的范围。     

Mie theory 1908, on the mobile phone 2008

Hundred years ago Gustav Mie published his famous paper on the theory of light scattering by spherical particles. It has been programmed in many programming languages since invention of the computer. Nowadays with the mobile phone becoming an educational tool it would be of interest to port a Mie scattering application to a Java enabled hand set. The objective of this paper is to investigate the feasibility of porting existing Mie software to a hand held device. We will show that the mobile phone can be an advanced programming environment for the Mie theory and we will present some exemplary computational results.