  The Rabi frequency (coupling strength) of an electric-dipole transition is an
important experimental parameter in laser-cooling and other atomic physics
experiments. Though the relationship between Rabi frequency and atomic
wavefunctions and/or atomic lifetimes is discussed in many references, there is
a need for a concise, self-contained, accessible introduction to such
calculations suitable for use by the typical student of laser cooling
(experimental or theoretical). In this paper, I outline calculations of the
Rabi frequencies for atoms with sub-structure due to orbital, spin and nuclear
angular momentum. I emphasize the physical meaning of the calculations.
