Proposal for studying bulk supercooled water using a magnetically levitated drop*

Levitation has become a useful technique in science and engineering to isolate, measure and manipulate macroscopic objects with high precision. We will describe a tabletop magneto-gravitational trap (fabricated from permanent magnets) that stably levitates diamagnetic materials, including silica and water. We have characterized the trapping potential by levitating silica microspheres with diameters ~50 μm and measuring their oscillations. The resonant frequencies measured along the trap's three principal axes agree with those predicted by numerical simulation. We also measure the sphere's first- and second- harmonic responses to an applied drive, which stem from the sphere's net charge and its dielectric response, respectively. A longer-term goal of this work is to address outstanding puzzles concerning supercooled water [1-3]. Since a levitated drop is removed from solid walls, vibrations, and impurities (all of which tend to reduce the stability of the supercooled phase), this approach represents a promising way to study the supercooled phase of water.