Peculiarities of the tunneling ionization of atoms and ions in a magnetic field

Abstract

We consider the tunneling ionization of an electron, bound by a zero-range potential and a constant magnetic field, under the influence of a low-frequency monochromatic laser beam. An integral equation for the complex quasienergy is derived based upon the exact solution of the Schr\"odinger equation and the Green's function earlier obtained by Rylyuk and Ortner [Phys. Rev. A 67, 013414 (2003)] for an electron moving in an arbitrary electromagnetic wave and a constant magnetic field. We show that accounting for an electron spin leads to drastic changes in ionization probability. For the case of a nonzero angle $\ensuremath{\theta}\ensuremath{\ne}0$ between an electromagnetic wave direction and the magnetic field the ionization rate is shown to increase with the magnetic field when the electron spin is taken into account. The expressions for the level shift and width and for the diamagnetic and the paramagnetic susceptibilities of the electron in a zero-range force field and a constant magnetic field are found. In the case of ionization of neutral atoms and positive ions, we also take into consideration the Coulomb interaction of the emerging electron with the atomic or ionic core.