Diagnostics of Microparticles on the Surface of Water

A new method of studying the properties and behavior of microparticles on the surface of liquids is proposed. According to this, the dynamics of polyamide-12 (PA-12) microgranules on the surface of water can be monitored using two techniques. In the first case, a drop of water containing granules is suspended on a glass substrate and viewed from below; the second case, a layer of water with PA-12 microparticles on the surface is observed from above. It is established that the microparticles in both cases are covered with a water film and do not contact with air, similar to glass microspheres with a density several times as low as that of water. As water evaporates, the microparticles remain fully immersed in small puddles. Using an interferometric technique, it was established that the deformation of water surface in suspended drop with PA-12 microgranules under the action of gravity cannot exceed several dozen nanometers. Observations showed that PA-12 microgranules with a density exceeding that of water stick to its surface while being localized beneath. Relationship of the proposed method with the experiment and theory for microparticles at the surface of liquid helium is traced.