Optical Absorption and Zeeman Spectra ofNd3+-Doped PbMoO4

The optical absorption and Zeeman spectra of PbMo${\mathrm{O}}_4$:${\mathrm{Nd}}^{3+}$ single crystals containing ${\mathrm{Na}}^{+}$ ions for charge compensation have been investigated between 5500 and 25 000 ${\mathrm{cm}}^{-1\mathrm{}}$ at temperatures of 4.2, 77, and 300°K. Polarization of the spectra has been helpful in identifying the crystalline Stark components of the $4f^3\mathrm{}\left[\mathrm{SL}\right]\mathrm{}$ $J$ levels of the ${\mathrm{Nd}}^{3+}$ ion. The experimental center of gravity for each of the 17 identified crystalline Stark-split $J$ levels can be interpreted using the parameters $E^1=4924.2\mathrm{}$, $E^2=24.3\mathrm{}$, $E^3=471.7\mathrm{}$, ${\zeta }_{4f}=879.1\mathrm{}$, $Y(22,1)=3455\mathrm{}$, and $Y(22,3)=-12020\mathrm{}$ all in ${\mathrm{cm}}^{-1\mathrm{}}$. The parameters $E^1$, $E^2$, $E^3$, and ${\zeta }_{4f}$ are associated with the isolated configuration $4f^3$. The parameters $Y(22,1)\mathrm{}$ and $Y(22,3)\mathrm{}$ represent the dominant contributions from nonlinear configuration interactions. The simultaneous least-squares fitting that produced this best set of parameters yielded an rms deviation of 38 ${\mathrm{cm}}^{-1\mathrm{}}$. Inclusion of parameters $\alpha$, $\beta$, and $\gamma$ of the linear theory of configuration interaction did not improve the agreement. First-order crystal-field-splitting calculations were carried out involving a total of 54 different crystalline Stark levels. Assuming $D_{2d}$ point-group symmetry for ${\mathrm{Nd}}^{3+}$ in the lattice, the best set of crystal-field-splitting parameters are $B_0^2=428.2\mathrm{}$, $B_0^4=-592.2\mathrm{}$,