"To see the world in a grain of sand...."

Solid and liquid particles, one to five microns in radius, are levitated in a quadrupole trap to study a variety of thermodynamic and optical properties. Currently Brownian rotation of solid particles and thermal fluctuation of the shape of liquid particles are being investigated through their effects on the light scattered by the particles.

Past studies include measurements of vapor pressures of pure liquids and solutions, the dynamics of condensation, light scattering from layered spheres, the explosion of electrically stressed liquid droplets, and the nucleation of various phase changes, including solid-solid structure changes, and liquid-solid transitions, both homogeneous and catalyzed.

The particles are produced using a device similar to an ink jet printer. They are charged and shot into a region of inhomogeneous electric field produced by electrodes having quadrupole geometry. The field varies harmonically in time and spatially contains a null point. The particle seeks the null point and may be trapped there indefinitely. Light scattering is used to monitor particle size and , in combination with gravity balancing electric forces, particle mass.