The3d→4ptransitions ofCu+in LiCl and of transition-metal ions in crystals

Abstract

An intense absorption band due to ${\mathrm{Cu}}^{+}$ in alkali halides has been observed. In LiCl:${\mathrm{Cu}}^{+}$ it occurs at 57 300 ${\mathrm{cm}}^{\ensuremath{-}1}$. Its three-dimensional oscillator strength is $f=0.070$. It is shown that this band is primarily a ${d}^{10}\ensuremath{\rightarrow}{d}^{9}p$ transition. The $d\ensuremath{\rightarrow}p$ transition energy in the crystal is substantially lower than in the free ion, although the $d\ensuremath{\rightarrow}s$ transition energy is higher. The near-uv bands are discussed in the light of this new observation. We believe that the present assignment opens the way for $3d\ensuremath{\rightarrow}4p$ band assignments in other ions in crystals, and several have been suggested.