Ionization dynamics of extended multielectron systems

Ionization of multielectron systems is investigated by using one-dimensional, multicon figuration time-dependent Hartree-Fock calculations. Our analysis reveals the key physical processes underlying ionization of complex systems. The laser-induced multielectron dynamics, and therewith the ionization process, depend on the ratio of laser frequency (omega(0)) to plasmon frequency (omega(p)). In the overresonant limit (omega(0)much greater thanomega(p)), tunnel ionization is destroyed and ionization takes place by a classical over the barrier mechanism. In the underresonant regime (w(0)much less thanw(p)), tunnel ionization remains dominant, but is weakened by a polarization-induced growth of the tunneling barrier.