Space-time dynamics of nanoparticles of a magnetofluid in a laser beam

Laser-induced space-time dynamics of nanoparticles of a magnetofluid was observed. Visualization was effectuated and the redistribution of the particles was measured. These showed a strong decrease in the particle density on and around the periphery of the laser beam axis. A number of proofs showing that the thermal diffusion of nanoparticles plays the key role in determining the dynamics of the particle redistribution are presented. High-quality pictures taken of the self-modulation of the laser beam serve as a new and powerful method for investigating transport phenomena and the nonlinear interaction of light with colloids. (C) 1998 American Institute of Physics. [S0021-3640(98)01419-4].