Forces on three-level atoms including coherent population trapping.

We present a calculation of the force on a stationary three-level atom excited by a nearly resonant Raman light field, which may be composed of an arbitrary combination of standing- and traveling-wave fields. The effects of the ground-state coherences are explicitly included and are shown to play a crucial role in the nature of the force on the atom. We show that the force contains terms that vary on length scales both shorter and longer than the optical wavelength and that the magnitude of these terms can be made arbitrarily large.