Abstract

The Cu⁺ ion in NaF, LiCl and NaCl shows weak near UV and strong vacuum UV sets of absorption bands, identifiable as 3d→4s and 3d→4p respectively.¹ The weak, temperature-dependent 4s transitions occur 1–2 eV higher in energy than in the free Cu⁺ ion, while the 4p bands lie 1–2 eV lower. The simplest interpretation of these facts is that the 4s electron is more strongly antibonding toward the ligands than are the 3d electrons, while the 4p electron is partly bonding and partly spread out beyond the nearest neighbor anion shell into the next neighbor cation shell. This general description was confirmed by the calculations of Harrison and Lin.²

© 1984 Optical Society of America