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

Abstract

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 by means of computer simulations using the Fokker-Planck equation and generalized Lorenz-Mie theory. Dynamic behaviour of the particles and a temporal correlation function of intensity fluctuations of the light scattered by these particles are calculated for various factors of particle size and power of the illuminating laser beam. Results of the simulations support the experimental observations of deformation in the temporal correlation functions of the scattered light and their dependences on the size of the particles and the power of the laser. From simulation results for the dynamics of particles, it is found that these changes in the correlation function arise from suppression of the random motion of the particles in the radial direction of the laser beam and induction of an average uniform motion in the beam propagation direction.