2011 年 26 巻 1 号 p. 24-29
When mist particles are generated from ethanol-water mixtures by ultrasonic atomization at a low temperature, ethanol is concentrated in the atomized mist particles. This paper explains the mechanisms of ethanol thickning in atomized droplets based on the cluster-level structures analysed by the mass spectrometry. When ultrasonic atomization of equimolar ethanol-water mixture is carried out at a lower temperature, e.g. 10°C, small clusters composed of only ethanol molecules can transfer from the liquid phase to the gas phase, while the large clusters consisting of both ethanol and water molecules cannot move across the interface. This leads to the thickning of ethanol in the atomized mist particles. The cluster-level structures of ethanol-water mixture, which varies with the ethanol concentration and the liquid temperature, directly determines the characteristics of ultrasonic atomization of ethanol aqueous solution.