Liquid micro-vortex generated around laser focal point in an intense high-frequency electric field

A micro-vortex was observed to occur in liquid films exposed to the combined action of a focused laser beam and a high-frequency electric field. The laser beam was perpendicular to both the surface of the liquid film and the direction of the electric field. The size of this optoelectrostatical microvortex (OEMV) in various liquids (water, ethanol, acetone, nitrobenzene) varied with the conditions of the experiment, but stayed in the 10 mu m range. The velocity of the liquid flow in the vortex could be controlled according to the intensity and frequency of the electric field (5*10/sup 4/ to 10/sup 6/ V/m, 2*10/sup 4/ to 10/sup 6/ Hz), laser power (0 to 2 W), and laser power density in the focal point. No microvortex was observed in benzene and chloroform. As an application of this phenomenon, single DNA molecules could be transported along the OEMV.<
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