The 4s- and 4p- XPS spectra of Xe, XeF2 and XeF4

The 4s- and 4p- XPS spectra of Xe gas, XeF2 molecule and XeF4 molecule are calculated by an ab-initio atomic many-body theory. The 4s-peak and the prominent '4p'-peak are predicted well by the present theory. In XeF2 and XeF4 the spectral lines observed below the 4d-double ionization threshold are the 4d-24f multiplet states strongly perturbed by the interaction with the initial 4p1/2-hole state. They are very similar to the spectral lines which emerge with an increase in atomic number (e.g. Ba)