Two-electron molecule in weak, strong, and ultrastrong laser fields: A one-dimensional model

We examine the interaction of a one-dimensional model molecule with two electrons and two nuclei in a very short pulse of light fields of different strength. Due to their high masses and the shortness of the pulse, the dynamics of the nuclei can be regarded as frozen during the pulse and only the electronic part of the wave function has to be taken into account. After the pulse the molecule will dissociate on a larger time scale if the electrons are not in a binding state, especially if both electrons are removed from the molecule. One finds that the ionization and dissociation probability decrease with increasing field strength for very high laser intensities, a phenomenon which is already known for the ionization of atoms. By examination of the shape of the wave function during the pulse one sees that the electrons are trapped in bound states of the time-averaged Kramers-Henneberger potential.