Polarized laser excitation, electron paramagnetic resonance, and crystal-field analyses of ${\mathrm{Sm}}^{3+}$-doped ${\mathrm{LiYF}}_4$

Using both optical absorption and laser-excited fluorescence, we have determined 55 crystal-field energy levels of the ${\mathrm{Sm}}^{3+}$ center in ${\mathrm{LiYF}}_4{:\mathrm{S}\mathrm{m}}^{3+}.$ Electron paramagnetic resonance determines the symmetry of the center to be tetragonal, with effective spin Hamiltonian parameters of $g_{\parallel }=0.410\mathrm{}\pm 0.005$ and $g_{\perp }=0.644\mathrm{}\pm \mathrm{0.002.}$ Inclusion of hyperfine interactions yields magnetic hyperfine constants of $A_{\parallel }=205\mathrm{}\pm 5\mathrm{MHz}$ and $A_{\perp }=735\mathrm{}\pm 5\mathrm{MHz}$ for the ${}^{147}\mathrm{Sm}$ isotope and $A_{\parallel }=165\mathrm{}\pm 5\mathrm{MHz}$ and $A_{\perp }=605\mathrm{}\pm 5\mathrm{MHz}$ for the ${}^{149}\mathrm{Sm}$ isotope. Truncating the ${4f}^5$ configuration to the lowest 30 multiplets, $D_{2d}$ symmetry crystal-field fits to the experimental energy levels yield physically reasonable crystal-field parameters with standard deviations under 11 ${\mathrm{cm}}^{\mathrm{-}1}$. Simultaneous diagonalization of the crystal- and magnetic-field perturbation matrices give calculated magnetic splitting factors in good agreement with the measured ground-state g factors.