Anomalies in the vacuum uv absorption spectrum ofYb3+in CaF2

Abstract

The vacuum uv absorption spectrum of ${\mathrm{Yb}}^{3+}$ in Ca${\mathrm{F}}_2$ shows marked differences from the consistent pattern of the other rare-earth ions. The differences suggest that the interaction between the ion and the crystal is unusually weak, possibly due to a contraction in the mean-square radius of the excited $5d$ electronic wave function.