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Spin-orbit interaction of Tm3+ - ground level and crystal field strength
摘要： The ground level 3H6 of Tm3+ ions in a number of crystals has been examined through the matrix elements of spin – orbit interaction. The latter have been determined comparable with the separation between 3H6 and the first excited level 3F4. The normalized ratios of spin – orbit interactions relative to the free ion value of Tm IV as a function of the scalar crystal field parameter Nv have been found to vary analogous to the nephelauxetic effect. The relationships between maximum splitting of 3H6, spin-orbit coupling constant, crystal-field parameters and the Nv have been also studied for the presented 42 stoichiometric or doped crystals containing Tm3+. The compounds include halogenides, organic complexes, oxides, oxohalides, and semiconductors.
关键词： Thulium (3+),Crystal field strength,Spin-orbit interaction,Ground level
更新于2025-09-23 15:22:29
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Intense red emission on dilute Mn-doped CaYAlO4-based ceramics obtained by laser floating zone
摘要： The laser floating zone (LFZ) technique was used to produce polycrystalline fibers composed by P21/c monoclinic Y4Al2O9 (YAM) and P?421m tetragonal CaYAl3O7 (CYAM) phases embedded into I4/mmm tetragonal CaYAlO4 matrix. The scanning electron microscopy and X-ray diffraction patterns put in evidence the strong effect of growth rate on the microstructural and phases’ evolution. Besides the microstructural and structural analysis, complementary optical techniques as photoluminescence (PL), PL excitation (PLE), and lifetime measurements were used to characterize the produced fibers. The nonintentionally doped fibers were shown to exhibit an intense deep red emission likely due to Mn4+ trace impurities. From the PLE measurements, average crystal field strength was estimated with Dq/B ~ 2.94. Temperature-dependent PL measurements revealed that the red luminescence is due to the overlap of transitions from the almost electronic degenerate 2E and 4T2 excited states to the 4A2 ground state. The emission from the two excited states arises due to the breakdown of the adiabatic approximation. The overall luminescence intensity of the red emission was found to decrease from 11 K to RT, and the internal quantum efficiency, estimated from the ratio of the integrated luminescence at high and low temperatures, was found to be 60%. Time-resolved spectroscopy indicates a single decay time of ca. 2.0 ms at room temperature, corresponding to the spin and parity forbidden 2E → 4A2 transition.
关键词： Laser floating zone,Crystal field strength,Polycrystalline fibers,Mn4+ trace impurities,Red emission
更新于2025-09-16 10:30:52