Comment on ‘‘Relation between copperLx-ray fluorescence and 2px-ray photoelectron spectroscopies’’

Kawai et al. [Phys. Rev. B 48, 8560 (1993)] concluded that for Cu compounds and high-${\mathit{T}}_{\mathit{c}}$ superconductors, there is a strong correlation between the ${\mathit{L}}_3$ x-ray emission spectroscopy (XES) spectrum satellite intensity and the 2${\mathit{p}}_{3/2}$ x-ray photoelectron spectroscopy (XPS) spectrum satellite intensity. They interpreted the XES satellite to be mainly due to the transition from the initial core-hole charge-transfer (CT) shakeup state rather than due to the ${\mathit{L}}_2$ ${\mathit{L}}_3$ ${\mathit{M}}_{4,5}$ Coster-Kronig (CK) decay preceding the ${\mathit{L}}_3$ ${\mathit{M}}_{4,5\mathrm{-}}$ ${\mathit{M}}_{4,5}$ ${\mathit{M}}_{4,5}$ spectator x-ray emission transition. One of the available experimental data shows that, despite a significant initial core-hole CT shakeup satellite intensity increase from metal Cu to high-${\mathit{T}}_{\mathit{c}}$ superconductors, the relative ${\mathit{L}}_3$ XES satellite intensity does not change at all because of the relative CK satellite intensity decrease. The latter is due to the decrease of the CK decay energy from metal Cu to high-${\mathit{T}}_{\mathit{c}}$ superconductors.