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

从理论和实验上研究了在激光辐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，以及相干光在高浓度粒子聚集系统中多次散射的时空特性。主要研究结果如下：1.布朗粒子的动力学行为：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被发现依赖于激光器的功率和束腰半径以及粒子尺寸。从使用Fokker-Planck方程和广义Lorenz-Mie理论的计算机模拟中阐明，粒子在径向和光束传播方向上的动力学变化是由于 ...更多信息 梯度力和散射力分量的激光束的辐射压力。研究还发现，当粒子半径大于束腰半径时，粒子在光束传播方向上的平动速度沿光束传播方向有两个沿着极大值，其位置与粒子尺寸直接相关.散射光的统计特性：由于粒子的动态行为的变化，散射光的强度波动的时间相关函数偏离理论值。时间相关函数的偏离程度强烈地依赖于粒子的尺寸以及激光束的功率和束腰半径。它表明，一个峰值强度分布和时间的相关时间的光多次散射后突然改变，由于在悬浮液中的颗粒的聚集。峰强度分布和相关时间的变化与微观和宏观尺度下粒子的空间性质密切相关。少

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