Multiple Ionization of Atoms in a Laser Field

Experimental and theoretical data on the process of multiply charged ion formation under laser interaction with atoms are analyzed. Based on this analysis a number of conclusions as to the nature of this process, as well as the nature of multielectron ionization, are made. A cascade process of multiply charged ion formation, which is most frequently realized in practice, is studied in detail. Arguments are provided in favour of the possibility of simultaneous detachment of several electrons under multiple ionization of atoms. The processes of electron detachment from the inner shells of atoms and ions, and formation of multiply charged ions under tunnel ionization, as well as in laser fields of subatomic and superatomic intensities, are also studied. Multiple ionization is shown to be a typical process observed in a wide range of experimental conditions, that is, for any atoms, different charge multiplicity of created ions, laser frequencies ranging from near UV to near IR, in multiphoton and tunnel ionization limits, and at laser intensities ranging from subatomic to superatomic. Consideration of experimental data confirms the conclusion of the great diversity of the multiple ionization process.