Ar valence-electron double-excitation satellites studied by high-energy photoelectron spectroscopy

The monochromatized x-ray (1487-eV photon energy) excited–valence-electron spectrum of argon, down to 70 eV binding energy, is presented. More than 25 satellite lines are observed. Several of these lie above the double-ionization thresholds. The intensity of the 3$s^2$3$p^4$ ${(\mathrm{}}^1$D)3d ${\mathrm{}}^2$S satellite line relative to the intensity of the 3s main line is 0.186(5) which substantially differs from the earlier reported (e,2e) measurements.