Interfacial Tension between Water and Selected Superheated Liquids by Quadrupole Oscillations of Drops.

摘要

A technique is presented for measuring the interfacial tension between two liquids, one of which may be in a metastable state. A drop of one liquid is acoustically levitated in the other liquid (host) and also acoustically driven into quadrupole shape oscillations. The frequencies associated with several phase angles near the quadrupole resonance of the drop and the diameter of the drop are measured, which allows the interfacial tension to be calculated given the densities of both the drop and the host liquids. Because the host liquid provides a very smooth and clean container for the levitated drop, and because the shape oscillation is excited acoustically, without contact with a solid surface, the drop may survive in the superheated state for a long enough time for the experiments to be conducted. A simplified model was developed for describing the free oscillation and forced oscillation of a drop freely suspended in a host. The results of the simplified model agree well with that of previous theories. The accuracy of this technique was tested by measuring the interfacial tension between water and each of two common liquids.