Photoionization of atoms in adiabatic approximation

Philip George Burke

V A Pazdzersky, Vladimir Yurovsky

Atom photoionization by the superposition of a fundamental field and its second harmonic is considered. The finite analytical expressions for the photoionization probability are obtained using the adiabatic approximation. They demonstrate that the photoelectron angular distribution has a polar symmetry when the electrical field strength has a maximal polar asymmetry and the distribution is asymmetrical when the field is symmetrical. A strict proof of the polar symmetry of the photoionization probability in the case of the electrical field with maximal asymmetry is deduced using the Keldysh-Faisal-Reiss theories. The obtained results are in agreement with the experimental data available.

James A. R. Samson, Anthony F. Starace

Benjamin Fain, Alex Boeglin, S. H. Lin

A general framework for description of quantum systems in strong external fields is established. The most important application of the theory is concerned with the multiphoton ionization of atoms and molecules. The adiabatic approximation is developed. The Hamiltonian of the system is diagonalized by a time-dependent unitary transformation, which generates an interaction energy vanishing for very slow fields. A general analysis of the photoionization rates is performed. A specific model is considered: one-dimensional motion in the δ-function potential and external harmonic electric field. This model allows the exact solution for time-dependent eigenvalues and eigenfunctions. These solutions are compared with the conventional free electron approach to the ionization states.

Steven Trent Manson

Jacek Matulewski, Andrzej Raczyński, Jarosław Zaremba

Atomic stabilization against photoionization is numerically investigated in two spatial dimensions. It is demonstrated that the stabilization, prevented by magnetic effects, can be restored by a properly chosen constant magnetic field.