Double photoionization processes in lithium

We have derived, from the measured double-to-single photoionization ratio of lithium, the double-photoionization cross-section for photon energies from the second double-ionization threshold (172.8 eV) up to 450 eV. Using a simple model to account for the different double-photoionization processes leading to a doubly charged Li ion, we compare the corresponding cross-sections with new time-dependent close-coupling calculations and find fairly good agreement.