Atomic charges in some copper compounds derived from XPS data

Abstract

Linear relationships between the core electron binding energies and atomic charges previously derived in our laboratory have been tested on XPS data for Cu2O, CuO, Cu(NO3)2 and CuFeS2, as well as for CuF2 and CuCl2. Atomic charges are obtained by combining these relationships with literature data on binding energies. This results in qCu = +0.38 for Cu2O; qCu = +1.02 for CuO, qCu = +1.37 for Cu(NO3)2, qCu= +0.15 for CuFeS2, qCu- +2.05 for CuF2 and qCu = +1.04 for CuCl2. These values are compared to recent theoretical estimates from the literature, giving qCu = +0.38 for Cu2O and qCu= +0.60 for CuO. The agreement is strikingly good for Cu2O. A calculated value of qCu for CuF2 is +1.44 and for CuCl2 +1.10. For Cu(NO3)2 theoretical calculations of qCu give values between 1.38 and 1.77. For CuFeS2, similarly, qCu= +0.07 has been reported. The purpose of this paper is to test and demonstrate the usefulness of the relations between core binding energies and charge. The agreement in most cases between experimental and theoretical charge values is therefore worth noting.