Nonperturbative Approaches to Atomic and Molecular Multiphoton (Half-Collision) Processes in Intense Laser Fields

Abstract

In this article, we describe some recent development of generalized Flo- quet formalisms and computational methods for nonperturbative treatments of atomic and molecular multiphoton (half-collision) processes in intense and superintense laser fields. We start with a brief review of the conventional Floquet matrix techniques, applicable to multiphoton bound-bound transitions in finite-level systems in periodic fields, and their limitations. Several generalized Floquet formalisms, beyond the Floquet theorem, are then introduced for the treatment of more complicated systems, such as the many-mode Floquet theory for multi-frequency laser excitation with non-periodic Hamil- tonians, the non-Hermitian Floquet formalism for bound-free and free- free multiphoton ionization and dissociation etc. Finally we describe several recent case studies of strong- field processes using the generalized Floquet techniques: intensity-dependent ionization potential and threshold shift, a.c. Stark shifts of Rydberg states in strong fields, above- threshold multiphoton detachment of H~ in one-color, two-color, and pulsed laser fields, stabilization and ionization suppression of negative ions in superintense high-frequency laser fields, and laser- induced chemical bond softening and hardening and molecular stabilization, etc.KeywordsLaser FieldSchrodinger EquationThreshold ShiftStark ShiftMULTIPHOTON ProcessThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.