Nondipole Ionization Dynamics of Atoms in Superintense High-Frequency Attosecond Pulses

Abstract

The ionization of $H(1s)$ in superintense, high-frequency, attosecond pulses is studied beyond the dipole approximation. We identify a unique nondipole 3rd lobe in the angular distribution of the ejected electron and show that this lobe has a well-defined classical counterpart. The ionization is likely to occur in the direction opposite to the laser propagation direction, which is fully understood from an analysis of the classical dynamics.