EXPERIMENT ON DIFFUSIOPHORESIS OF AEROSOL-PARTICLES AT LOW KNUDSEN NUMBERS

The velocity of diffusiophoresis accompanying the Stefan flow was expe rimentally studied for a Knudsen number of 0.13. Water, ethanol, tolue ne and ethyl acetate were used as the diffusing vapor. The vapor press ure gradient and temperature gradient were formed in a space between h orizontal parallel plates at different temperatures (the upper plate h as the higher temperature) and being wetted by a liquid. A singly char ged standard polystyrene latex (PSL) particle (1.00 mum) was suspended in that space under atmospheric pressure and was balanced by applying a dc. voltage to the parallel plates. This method actually measures t he resultant force of thermophoresis and diffusiophoresis, and the the rmophoretic force separately measured in vapor free conditions was sub tracted to obtain the diffusiophoretic force. The results thus obtaine d were found to be in good agreement with Waldmann's theory.