Two-photon one-electron ionisation cross section of the 5p shell of xenon including screening effects

The authors present calculations of the two-photon one-electron ionisation of the 5p shell of xenon including non-linear response. Screening effects are described within the random-phase approximation (RPA). The authors use both a local-density approximation (LDA) and a Hartree-Fock average basis set. They describe a large energy region from the two-photon ionisation threshold to above the one-photon ionisation threshold ('above-threshold-ionisation' process, ATI). They demonstrate the importance of many-electron screening effects; and in particular point out the role of double excitation mechanisms.