Rate equations versus Bloch equations in multiphoton ionization

The Wilcox-Lamb method of deriving rate equations from Bloch equations is outlined using as an example a two-level atomic model. Computer-generated plots directly comparing solutions of these rate equations and of Bloch equations for a three-level atomic model are illustrated. Two cases of interest are discussed: copropagating and counterpropagating laser beams. Some comments concerning collisional accessing and ionizing of atoms in a very broad Doppler profile are made.