Dynamics and light-scattering properties of Brownian particles in suspensions under laser radiation pressure

激光辐射压力下悬浮液中布朗粒子的动力学和光散射特性

• 批准号: 09450024
• 负责人: ASAKURA Toshimitsu
• 金额: $ 6.08万
• 依托单位: Hokkai-Gakuen University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09450024/
• 关键词: Radiation pressure of light; Dynamic light scattering; Brownian motion; Photophoresis; Fokker-Planck equation; generalized Lorenz-Mie theory; Enhanced backscattering; fractal aggregates; Monte-Carloシミュレーション

Dynamics and light-scattering properties of Brownian particles in colloidal suspensions under the influence of the radiation pressure force of an illuminating laser beam are investigated theoretically and experimentally.Spatial and temporal properties of coherent light multiply scattered backward by the highly concentrated system of particles with aggregations have also been investigated theoretically and experimentally. The main results are summarized in the following:1. Dynamic behavior of the Brownian particles: Suppression of the Brownian motion of the particles in radial direction of the laser beam and induction of translational motions in the beam propagation direction are found to have dependencies on power and beam-waist radius of the laser and particle size. It is clarified from computer simulations using the Fokker-Planck equation and the generalized Lorenz-Mie theory that the changes in the dynamics of the particles in the radial and beam propagation directions are due to a … More gradient force and scattering force components of the radiation pressure of the laser beam, respectively. It is also found that, if the particle radius is larger than the beam-waist radius, velocity of the translational motion of the particle in the beam propagation direction has two maxima along the beam propagation direction and their positions are directly related to the particle size.2. Statistical properties of the scattered light: As a result of the changes of dynamic behavior of the particles, a temporal correlation function of intensity fluctuations of the scattered light deviates from theoretical one. Degree of the deviations in the temporal correlation function is strongly dependent on the the size of the particles and the power and beam-waist radius of the laser beam. It is demonstrated that a peak intensity distribution and a temporal correlation time of the light multiply scattered backward change suddenly due to aggregation of particles in suspensions. These changes in the peak intensity distribution and the correlation time are closely related to spatial properties of the particles in both microscopic and macroscopic scales. Less

本文从理论上和实验上研究了在激光照射压力作用下，胶体悬浮液中布朗粒子的动力学和光散射特性。本文还从理论和实验两方面研究了高度聚集粒子系统反向散射相干光的时空特性。主要研究结果总结如下：布朗粒子的动力学行为：发现粒子在激光束径向上的布朗运动的抑制和在光束传播方向上的平移运动的诱导与激光的功率、束腰半径和粒子尺寸有关。利用Fokker-Planck方程和广义Lorenz-Mie理论进行的计算机模拟表明，粒子在径向和光束传播方向上的动力学变化分别是由于光束辐射压力的梯度力和散射力分量的增加而引起的。还发现，当粒子半径大于束腰半径时，粒子在束传播方向上的平移运动速度沿束传播方向有两个极大值，它们的位置与粒子大小直接相关。散射光的统计特性：由于粒子动力学行为的变化，散射光强度波动的时间相关函数偏离了理论相关函数。时间相关函数的偏差程度与粒子的大小、激光束的功率和束腰半径密切相关。结果表明，由于悬浮液中粒子的聚集，光散射后向的峰强度分布和时间相关时间发生了突然的变化。这些峰值强度分布和相关时间的变化与颗粒在微观和宏观尺度上的空间性质密切相关。少

项目成果

Yasuhiro Harada: "Sizing method for biological particles in suspensions using laser trapping techniques"Proceedings of OWLS VI. (submitted). (2000)

Yasuhiro Harada：“使用激光捕获技术对悬浮液中的生物颗粒进行分级方法”OWLS VI 论文集。

K.Ishii: "Optical free-path-length distribution of in a fractal aggregate and its effect on enhanced backscattering" Applied Optics. 37(21). 5014-5018 (1998)

K.Ishii：“分形聚合中的光学自由程长度分布及其对增强后向散射的影响”应用光学。

T. Iwai: "Space-time statistics of the coherent light backscattered from fractal and nonfractal random media with absorption" Proceedings of SPIE. 2982. 104-105 (1997)

T. Iwai：“具有吸收作用的分形和非分形随机介质反向散射的相干光的时空统计”SPIE 论文集。

Yasuhiro Harada: "Computer simulation of dynamics and light-scattering properties of Brownian particles under the laser radiation pressure"Proceedings of SPIE. 3252. 99-106 (1998)

原田泰弘：“激光辐射压力下布朗粒子动力学和光散射特性的计算机模拟”SPIE 论文集。

Katsuhiro Ishii: "Monitoring of the cluster growth in the colloidal suspension using a diffusive wave spectroscopic technique"Proceedings of SPIE. 3599. 76-85 (1999)

Katsuhiro Ishii：“使用扩散波光谱技术监测胶体悬浮液中簇的生长”SPIE 论文集。