Landau-Dykhne approach for relativistic electron momentum and angular distributions for the ionization of multicharged atomic ions by superintense laser fields

摘要

Analytic expressions are obtained for relativistic electron momentum and angular distributions in the tunneling and barrier-suppression ionization of multicharged atomic ions by a superintense linearly polarized field. The Landau-Dykhne approach is used for derivation of these distributions. The condition for applicability of this adiabatic approximation requires that an ejected electron should have sufficiently high kinetic energy so that the ionization probability should be exponentially small. The electron momentum can be both less and larger than the relativistic quiver momentum. In the vicinity of the quiver momentum we found a new peculiarity: sharp cusp in the momenum distribution along the polarization of laser radiation. It is absent at the nonrelativistic ionization of atomic ions by moderate laser fields. The electron momentum spectra along the laser electric field and along the laser magnetic field do not depend on the sign of momentum. In contrast, the relativistic momentum spectra along the direction of propagation of laser radiation and along in the opposite sense are significantly different.