Showing papers by "Hans P. Jenssen published in 1975"

Analysis of the optical spectrum of Tm 3 + in LiY F 4

Abstract: Absorption and fluorescence spectra of ${\mathrm{Tm}}^{3+}$ in single-crystal LiY${\mathrm{F}}_{4}$ were recorded at temperatures between 5 and 77 K. The energy levels for the ground configuration were established from these data with the aid of theoretical calculations. Parameters were obtained that gave a least-squares deviation of 16.9 ${\mathrm{cm}}^{\ensuremath{-}1}$ between the experimental and calculated energy levels. These calculated levels were obtained by diagonalizing a Hamiltonian that describes the free-ion and crystal-field interactions in a basis of states spanning the $4{f}^{12}$ configuration. The free-ion parameters are ${F}_{2}=462.49$, ${F}_{4}=70.762$, ${F}_{6}=7.6265$, $\ensuremath{\zeta}=2652.8$, $\ensuremath{\alpha}=23.262$, $\ensuremath{\beta}=\ensuremath{-}761.64$, ${M}_{0}^{(0)}=3.2459$, ${M}^{(0)}=1.4608$, ${M}^{(2)}=0.8202$, and ${M}^{(4)}=0.5572$, and the crystal-field parameters are ${B}_{20}=358.7$, ${B}_{40}=\ensuremath{-}607.8$, ${B}_{60}=\ensuremath{-}173.0$, ${B}_{44}=844.2$, and ${B}_{64}=629.2$ (all units are ${\mathrm{cm}}^{\ensuremath{-}1}$). The calculated and crystal-field-split energy levels were in agreement to within 9 ${\mathrm{cm}}^{\ensuremath{-}1}$ after the calculated energy centroids were adjusted. The ${S}_{4}$ symmetry property of the ground state was determined to be ${\ensuremath{\Gamma}}_{2}$.