X-ray photoemission measurements of NaCuO2 samples and reference mater
ials have been made to study the electronic structure of the copper io
ns and the Cu-O interaction in these materials. Cu 2p3/2 spectra of Cu
2O, CuO and NaCuO2 compounds are compared. The results are discussed i
n terms of three formal oxidation states of copper. The chemical shift
s of the Cu 2p lines are in good agreement with recent theoretical val
ues.