  We investigate dynamics and interactions of particles levitated and trapped
by the thermophoretic force in a vacuum cell. Our analysis is based on footage
taken by orthogonal cameras that are able to capture the three dimensional
trajectories of the particles. In contrast to spherical particles, which remain
stationary at the center of the cell, here we report new qualitative features
of the motion of particles with non-spherical geometry. Singly levitated
particles exhibit steady spinning around their body axis and rotation around
the symmetry axis of the cell. When two levitated particles approach each
other, repulsive or attractive interactions between the particles are observed.
Our levitation system offers a wonderful platform to study interaction between
particles in a microgravity environment.
