Ionization dynamics of extended multielectron systems

Ionization of multielectron systems is investigated by using one-dimensional, multiconfiguration 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 (ω₀) to plasmon frequency (ωₚ). In the overresonant limit (ω₀⪢ωₚ), tunnel ionization is destroyed and ionization takes place by a classical over the barrier mechanism. In the underresonant regime (ω₀⪡ωₚ), tunnel ionization remains dominant, but is weakened by a polarization-induced growth of the tunneling barrier.