Interaction of laser radiation with a negative ion in the presence of a strong static electric field

Authors

• N. L. Manakov, Voronezh State UniversityFollow
• M. V. Frolov, Voronezh State University, RussiaFollow
• Anthony F. Starace, University of Nebraska-LincolnFollow
• Ilya I. Fabrikant, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2000

Comments

Published in Journal of Physics B: Atomic, Molecular and Optical Physics 33 (2000), pp. R141–R214. Copyright © 2000 IOP Publishing Ltd. Used by permission.

Abstract

This paper provides a general theoretical description of a weakly bound atomic system (a negative ion) interacting simultaneously with two (generally strong) fields, a static electric field and a monochromatic laser field having an arbitrary elliptical polarization. The zero-range δ-potential is used to model the interaction of a bound electron in a negative ion as well as the interaction of a detached electron with the residual atom. Our treatment combines the quasistationary (complex energy) and quasienergy (Floquet) approaches. This quasistationary, quasienergy state (QQES) formalism is the most appropriate one for analysing a decaying quantum system under the influence of a periodic external perturbation. Existing QQES theory is reviewed and some new results are discussed: the Hellmann–Feynman theorem and the normalization procedure for QQES, and the definition of the dipole moment and the dynamic polarizability for a decaying atomic system (in strong static electric and/or laser fields). These results are illustrated using analytical formulae obtained from an exact solution of the QQES problem for a δ-model potential in two strong fields. Finally, from the imaginary part of the dynamic polarizability we obtain analytic results (to first order in the laser-field intensity) for the photodetachment cross section. Our results are then compared with those of previous theoretical studies.