Experimental and Theoretical Study of the Low-Lying Energy-Level Structure ofSm3+in CaF2

Abstract

The optical spectrum exhibited by the ${\mathrm{Sm}}^{3+}$ ion in Ca${\mathrm{F}}_2$ is analyzed assuming both octahedral and trigonal site symmetries. Calculations were performed using a tensor operator technique in the complete intermediate-coupling scheme. The crystal field parameters and the root-mean-square (rms) deviations obtained are $B^{\mathrm{}\left(4\right)\mathrm{}}=-906\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$ and $B^{\mathrm{}\left(6\right)\mathrm{}}=618\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$ with rms deviations of 48.1 ${\mathrm{cm}}^{-1\mathrm{}}$ for the octahedral site symmetry; $B_0^{\mathrm{}\left(2\right)\mathrm{}}=118\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$, $B_0^{\mathrm{}\left(4\right)\mathrm{}}=-272\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$, $B_3^{\mathrm{}\left(4\right)\mathrm{}}=-296\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$, $B_0^{\mathrm{}\left(6\right)\mathrm{}}=38\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$, $B_4^{\mathrm{}\left(6\right)\mathrm{}}=-128\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$, and $B_6^{\mathrm{}\left(6\right)\mathrm{}}=1556\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$, with rms deviation of 35.4 ${\mathrm{cm}}^{-1\mathrm{}}$ for the trigonal site symmetry. It is suggested that the sample on which the measurements were carried out contains ${\mathrm{Sm}}^{3+}$ ions occupying both octahedral and trigonal symmetry sites. It is also shown that crystal field theory with a single set of $B_q^{\mathrm{}\left(k\right)\mathrm{}}$ parameters is quite adequate to describe the energy levels lying below 11 000 ${\mathrm{cm}}^{-1\mathrm{}}$, above which a fairly large energy gap follows.