LOW-POWER LASER DRIVING OF A BINARY-LIQUID

We have investigated the interaction of a laser beam with a near-criti cal binary liquid by observing how the growth of the concentration gra dient due to gravity (the barodiffusion gradient) is modified by the p resence of the beam. We observe definite evidence of laser driving in the system: The size of the steady-state barodiffusion gradient increa ses with increasing laser power, and the system exhibits different dyn amical behaviors in the limit of high and low powers. Since our result s cannot be explained by a purely diffusive model, we conclude that co nvection must be important in the system and present an estimate of th e laser power at which convection should become significant. [S1063-65 1X(98)10510-X].