Calculation of Ar photoelectron satellites in hard X-ray region
  The intensities of photoelectron satellite lines, corresponding to double core hole (DCH) states of Ar 1s ionization by hard X-rays are calculated using the many-body-perturbation theory. Calculations support the interpretation of the most intense lines as the shake-up excitations 2p 4p. It is demonstrated that the intensities of the spectrum lines corresponding to 4s (and 3d) excited states in DCH field can be explained only taking into account the direct knock-up process 2p 3d along with shake-up process 1s 4s that accompanies 2p photoionization. 
V.G. Yarzhemsky, M.Ya Amusia
physics.atom-ph