Magnetic circular dichroism of off-centeredCu+and on-centeredCu+in alkali halides

Optical-absorption and magnetic-circular-dichroism (MCD) spectra of off-centered ${\mathrm{Cu}}^{+}$ in KI, KBr, and KC1 crystals and of on-centered ${\mathrm{Cu}}^{+}$ in NaC1 crystals are investigated at temperatures from 80 to 300 K. In KI: ${\mathrm{Cu}}^{+}$ an absorption band due to the $d^{10}\to d^{9}p$ allowed transition is observed in addition to six absorption bands due to the $d^{10}\to d^{9}s$ forbidden transition. Different MCD line shape and temperature dependence are observed between the off-centered ${\mathrm{Cu}}^{+}$ and on-centered ${\mathrm{Cu}}^{+}$. A discussion is given on the level assignment for the ${\mathrm{Cu}}^{+}$ absorption bands observed in KI.