Ultrasonic Irradiation Effect in Supercooled Liquids of Naphthalene

Solidification of the supercooled liquids of naphthalene was influenced by ultrasonic irradiation. The solidification temperatures, Ts, of the supercooled liquids of naphthalene were independent of applied ultrasonic transducer power, though Ts under no ultrasonic irradiation decreased. By isothermal holding above Ts, incubation time was greater than zero only under ultrasonic irradiation until the supercooled liquids of naphthalene solidified. Moreover, incubation time increased at fixed temperature with increasing holding temperature or applied transducer power. In optical microscopy observation, the fractal distribution of microstructures was observed in the sample, which solidified under ultrasonic irradiation without isothermal holding. These results are due to the anomalous nucleation caused by the local pressure induced by ultrasonic waves.