The objective of this grant is the formulation of a tractable theory for treating ionization of atoms by laser fields too intense to be regarded as a perturbation. The calculation of ionization rates to specific channels poses a challenging problem. The divergent integrals inherent in dealing with transitions through the continuum will be handled by working in the velocity gauge and algebraically manipulating the cancellation of divergences. Some "nonperturbative" methods are proposed. Other problems associated with multiphoton ionization of atoms will also be explored.
