  Quantum mechanical scattering theory is studied for time-dependent
Schroedinger operators, in particular for particles in a rotating potential.
Under various assumptions about the decay rate at infinity we show uniform
boundedness in time for the kinetic energy of scattering states, existence and
completeness of wave operators, and existence of a conserved quantity under
scattering. In a simple model we determine the energy transfered to a particle
by a collision with a rotating blade.
