Fundamental Aspects of Atomic Photoionization with High-Brightness Light Sources

Resonant 3p photoelectron spectroscopy of free Cu atoms

“…The accuracy achieved in the present data allows the confirmation of a slight asymmetry of the resonance profiles, corresponding to a negative q-parameter with a large (q > 10) but finite absolute value (q = 25±15), which was predicted by atomic many-body calculations [3,4,13]. The importance of inter-channel coupling [15] between the resonant 3d 8 ( 1 G)4s 2 εl satellite channel and the main channel 3d 9 4sεl was stressed by Combet Farnoux [3] in order to explain this asymmetry. Neglecting this coupling would result in a symmetrical profile since the nonresonant quadrupole shake-up 3d 10 4s → 3d 8 ( 2S+1 L)4s 2 εl ionization requires a 1 D coupling of the 3d 8 core [14].…”

Two-electron processes in multiple ionization under strong soft-x-ray radiation

“…Cowan's code, which has been found quite adequate in such a context [31], offers the necessary flexibility for the task. The two-photon cross sections σ (2) 76 and σ (2) 87 were calculated with the single-channel quantum defect theory. Its accuracy was tested by trial calculations for systems for which values of cross sections obtained through other methods were available.…”

“…The process has been studied both theoretically (Refs. [1][2][3] and references therein) and experimentally (Refs. [3][4][5] and references therein) in a variety of systems, as it demonstrates in a direct way the limits of, and deviations from, the simple one-electron pictures.…”