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A numerical method for solving the time-dependent Schrödinger equation for a one-electron atomic system in an intense, short-pulsed laser field is presented. An effective potential formalism is proposed and tested for representing the excitation of the valence electrons in rare gases. Results for ion production yields, photoelectron distributions and harmonic conversion are presented and compared to recent experimental results. [ABSTRACT FROM AUTHOR]

Using Rydberg atoms and microwave fields it has been possible to observe virtually all one electron strong field phenomena. The attraction of these experiments is that they can be more controlled than most laser experiments, with the result that more quantitative information can be extracted. The insights gained from these experiments can be profitably transferred to optical experiments. To demonstrate the latter point we demonstrate that apparently non-resonant microwave ionization, in fact, occurs by resonant transitions through intermediate states. These experiments demonstrated clearly the power of Floquet analysis of such processes, and the ideas were subsequently applied to the analogous problem of laser multiphoton ionization. [ABSTRACT FROM AUTHOR]

One-electron atoms subjected to a time-dependent external field provide physically realistic examples of scattering systems with chaotic classical dynamics. Recent work on atoms subjected to a sinusoidal external field or to a periodic sequence of instantaneous kicks is reviewed with the aim of exposing similarities and differences to frequently studied abstract model systems. Particular attention is paid to the fractal structure of the set of trapped unstable trajectories and to the long time behavior of survival probabilities which determine the ionization rates of the atoms. Corresponding results for unperturbed two-electron atoms are discussed. [ABSTRACT FROM AUTHOR]

To afford a basis for constructing Thomas-Fermi-like approximations to the electronic structure of atoms in intense applied fields, the canonical density matrix (or equivalently the Feynman propagator) for free electrons is first set up. This is done for both intense magnetic and intense electric fields: in each case, exact results are available for arbitrary static field strengths. Physical properties of atoms and ions in intense magnetic fields are hence obtained in the statistical limit of Thomas-Fermi theory. This discussion is then supplemented by the ‘hyperstrong' limit, considered especially by Lieb and co-workers. Chemistry in intense magnetic fields is thereby compared and contrasted with terrestrial chemistry. Some emphasis is then placed on a model of confined atoms in intense electric fields: the statistical Thomas-Fermi approximation again being the central tool employed. [ABSTRACT FROM AUTHOR]

In the presence of a homogeneous magnetic field the center of mass and internal motion of a neutral or charged two-body system cannot be separated. We review the effects and phenomena which occur due to the inherent two-body character of these systems. The most prominent effects that occur for neutral species are the chaotic classical diffusion of the center of mass, the intermittent near-threshold behavior and the appearance of weakly bound states with an extraordinarily large electric dipole moment in crossed electric and magnetic fields. For ionic two-body systems the regions of strong mixing of the center of mass and internal motion are identified and investigated. As major effects we observe the classical self-stabilization as well as selfionization processes of the ion. [ABSTRACT FROM AUTHOR]

When molecules are subjected to intense laser fields, they undergo multielectron dissociative ionization (MEDI), a process that is, as yet, little understood. This chapter gives a brief overview of some of the experimental techniques used to study the process. At present there are two models that attempt to explain the facts, inertial confinement (with rapid ionization at a critical inter-ion separation) and laser-induced stabilisation. In order to ascertain which, if either, of these models is correct, more definitive experiments are required, involving interferometric control of laser parameters, good laser characterisation, and a more careful analysis of the dissociation dynamics. [ABSTRACT FROM AUTHOR]