Induced dipole effect in strong-field photodetachment of atomic negative ions

The process of strong-field photodetachment of an atomic negative ion is considered with a simple analytical account for the ac dipole moment induced in the atomic core by the external laser field. The method is based on a Keldysh-like saddle-point theory, modified by using dipole-spherical angular wave functions in the initial state of the outer electron. The field-induced dipole results in an increase of the detachment rate and essential modifications in its angular dependence. These modifications are interpreted as destruction of the quantum interference originated from the coherent superposition of the two saddle-point contributions to the transition amplitude.