Multiplet contributions to the2p32x-ray photoemission spectrum of CuO

The electronegativity of the Cu(II) ligand is shown to influence the $2p_{\frac{3}{2}}$ x-ray photoemission spectrum of the Cu cation: hybridization will cause the main peak character to lie between $d^9$ and $d^{10}$, with the lower value being approached as the ligand electronegativity decreases. Thus, on $p$ electron emission, there is an increased propensity for $p^5{d}^9$ multiplet splitting of the main peak. This manifests itself as a broadening of the main peak, along with a commensurate narrowing of the satellite peak. These findings, and their limitations, have direct application to the study of superconducting ceramics.