Triple photoionization of lithium near threshold

Solving the full classical four-body Coulomb problem numerically using a Wigner initial distribution, we formulate a classical-quantum hybrid approach to study triple ionization by single photon absorption from the Li ground state in the threshold region. We confirm the Wannier threshold law σ ∝ E^α, and we show that α determined in the interval between 2 and 5 eV deviates from the analytical threshold value of 2.16 which we find in the interval between 0.1 and 2 eV.