Uygun V. Valiev

Absorption intensities and emission cross sections of Tb3+ (4f8) in TbAlO3

Trivalent terbium absorption intensities in single-crystal TbAlO3 are analyzed using the Judd-Ofelt model to assess the crystal’s potential as a solid state laser system. The standard Judd-Ofelt model was applied to the room temperature absorption intensities of Tb3+ (4f8) to determine the phenomenological intensity parameters Ω2, Ω4, and Ω6. Seven multiplet manifolds are identified and the absorption intensities of these manifolds are least-squares fitted to the calculated intensities to obtain the intensity parameters: Ω2=40.52×10−20cm2, Ω4=8.74×10−20cm2, and Ω6=2.26×10−20cm2 in TbAlO3. These intensity parameters are then applied to determine the radiative decay rates and branching ratios of Tb3+ transitions from the D45 to the FJ′7 multiplet manifolds. Based on the results, the radiative lifetime of the excited state manifold D45 is determined from the radiative decay rates and found to be 3.5ms. The calculated lifetime is longer than the measured lifetime, reflecting the nonradiative interactions betw...

Energy levels of Dy3+(4f 9) in orthoaluminate crystals

A detailed crystal-field splitting analysis is reported for the energy levels of Dy3+(4f9) in crystals of YAlO3 and DyAlO3 orthoaluminates. Experimental energy (Stark) levels for the 15 lowest-energy 2S+1LJ multiplet manifolds of Dy3+ are reported and supplemented with values found in the literature. A parameterized Hamiltonian, including Coulombic, spin-orbit, configuration interaction, and crystal-field terms in Cs symmetry, was diagonalized for the 6HJ, 6FJ, 4FJ, 4IJ, and 4GJ states. Initial sets of crystal-field parameters were determined from lattice-sum calculations and the three-parameter theory. Considerable J-mixing is found for states having nearly the same energy such as the manifolds 6F11/2, 6H9/2, and 6F9/2, 6H7/2. Even states that are well separated from each other in energy show sufficient J mixing to explain the polarized absorption and Zeeman effects that involve transitions from the nearly pure (less than 0.2% J mixing) ground state, 6H15/2 to excited states such as 6F5/2 and 6F3/2. The ...

Modeling optical transitions of Er3+(4f11) in C2 and C3i sites in polycrystalline Y2O3

The optical properties of Er3+ in polycrystalline (ceramic), and nanocrystalline forms of cubic (bixbyite) yttrium oxide are modeled based on the absorption spectra obtained between 400 and 1700 nm and the fluorescence spectra observed between 1500 and 1670 nm. Both spectra were obtained at 8 K. The observed crystal-field splitting and the measured intensities of transitions between Stark levels of the L2S+1J multiplet manifolds of Er3+(4f11) in both the C2 and C3i sites of Y2O3 are analyzed in terms of established models. The inversion symmetry of C3i sites limits the observed electronic transitions to magnetic dipole transitions between the I413/2 and I415/2 manifolds. There is no spectroscopic evidence for transitions involving other multiplet manifolds of Er3+ ions in C3i sites. For Er3+ ions in C2 sites, forced electric dipole transitions are allowed between the J+12 Stark levels associated with each manifold. With few exceptions, the crystal-field splitting and the intensities of the transitions bet...

Specific features of Eu3+ and Tb3+ magnetooptics in gadolinium-gallium garnet (Gd3Ga5O12)

Abstract We reported magnetooptical properties of Eu3+(4f(6)) and Tb3+(4f(8)) in single crystals of Gd3Ga5O12 (GGG), Y3Ga5O12 (YGG), and Eu3+(4f(6)) in Eu3Ga5O12 (EuGG) for both ions occupying sites of D2 symmetry in the garnet structure. Absorption, luminescence, and magnetic circular polarization of luminescence (MCPL) spectra of Tb3+ in GGG and YGG and absorption and magnetic circular dichroism (MCD) of Eu3+ in EuGG were studied. The data were obtained at 85 K and room temperature (RT). Magnetic susceptibility of Eu3+ in EuGG was also measured between 85 K and RT. The magnetooptical and magnetic susceptibility data were modeled using the wavefunctions of the crystal-field split energy (Stark) levels of Eu3+ and Tb3+ occupying D2 sites in the same garnets. The results reported gave a precise determination of these Stark level assignments and confirmed the symmetry labels (irreducible representations) of the closely-spaced Stark levels (quasi-doublets) found in the 5D1 (Eu3+) and 5D4 (Tb3+) multiplets. Ultraviolet (UV) excitation (

Analyses of the optical and magneto-optical spectra of Tb3Ga5O12

Absorption spectra of the FJ7, D4,3,25, G6,5,45, and L10,95 multiplet manifolds of Tb3+ (4f8) in D2 sites in cubic garnet Tb3Ga5O12 (TbGaG) are investigated at sample temperatures between 1.8K and room temperature. Absorption measurements extend from 5000to340nm. From analyses of temperature-dependent (hot-band) absorption spectra, many of the crystal-field split energy (Stark) levels of the LJ2S+1 multiplet manifolds of Tb3+ are identified and confirmed from analyses of the fluorescence spectra observed between 485 and 680nm, representing transitions from the D45 to the FJ7 manifolds. Each manifold is split by the crystal field into 2J+1 Stark levels. Some of these manifolds, including the ground-state manifold F67, consist of Stark levels that are accidentally degenerate, or nearly so, making transitions to or from these levels appear as unresolved spectra, even at the lowest temperature investigated (1.8K). To resolve these spectra, we have investigated the Zeeman and magneto-optical spectra for repres...

Modeling optical spectra and Van Vleck paramagnetism in Er3+:YAlO3

Low-temperature absorption spectra are reported for Er3+:YAlO3 (YAP) between 1700 and 350 nm. The low-temperature vacuum ultraviolet absorption spectra are also reported between 400 and 190 nm. A total of 134 experimental energy (Stark) levels representing 30 multiplets with energies below 44 000 cm−1 were modeled using a parametrized Hamiltonian defined to operate within the 4f11 electronic configuration of the Er3+ ions substituting for Y3+ in YAP, an orthorhombically distorted perovskite. The Y3+ sites have low symmetry (CS). The crystal-field energy-level parameters were determined through use of a Monte Carlo method in which 14 independent parameters are given random starting values, which are optimized using standard least-squares fitting between calculated and experimental levels. The best solution obtained has a standard deviation of 6.92 cm−1 (rms error of 6.09 cm−1). In the presence of a magnetic field the Er3+ ions occupy two magnetically inequivalent sites. As an independent check of the cryst...

Energy levels and symmetry assignments for Stark components of Ho3+(4f10) in yttrium gallium garnet (Y3Ga5O12)

Absorption and fluorescence spectra observed between 1950 and 320 nm at sample temperatures of 8, 78, and 293 K, representing more than 900 transitions between 24 multiplets L2S+1J of Ho3+(4f10) split by the crystal field, have been analyzed in Czochralski-grown single crystals of Ho3+ doped-yttrium gallium garnet (Y3Ga5O12 or YGG). The Ho3+ ions replace Y3+ ions in sites of D2 symmetry during crystal growth. Associated with each multiplet manifold are 2J+1 nondegenerate crystal-field split sublevels (Stark levels) characterized by one of four different irreducible representations (irreps) associated with D2 symmetry. The energy and irrep assignments for individual experimental Stark levels were established by an algorithm that makes use of the selection rules for electric-dipole (ED) and magnetic-dipole (MD) transitions between Stark levels. Nearly degenerate Stark levels (quasidoublets) in several manifolds have been observed and investigated by magneto-optical methods reported in a separate study. Of t...

Magnetooptics of the 1D2 → 3F4 radiative transition in thulium:yttrium-aluminum garnet Tm3+:YAG

The spectra of luminescence and magnetic circular polarization of luminescence in the 1D2 → 3F4 emission band in thulium:yttrium-aluminum garnet Tm3+:YAG (Tm3+:Y3Al5O12) have been investigated at temperatures T = 78 and 293 K, respectively. Based on the analysis of the magnetooptical and optical spectra, the optical transitions between the Stark sublevels of the 3F4 and 1D2 multiplets in Tm3+:YAG were identified. It is shown that the symmetry and energies of the Stark sublevels of the 3F4, 1D2, and 3H6 multiplets, found experimentally from magnetic and magnetooptical studies, confirm the results of theoretical calculations of the energy spectrum of the rare earth Tm3+ ion in YAG.

Specific features of magneto-optical spectra of Tb3Ga5O12

The spectra of magnetic circular dichroism in the range of the 7F6→5D4 absorption band and the spectra of magnetic circular polarization of luminescence in the range of the 5D4→7F5 band in the terbium-gallium garnet Tb3Ga5O12 are studied at a temperature of 80 K. The optical transitions between the Stark sublevels of the 7F6, 7F5, and 5D4 multiplets are identified based on the analysis of the magneto-optical and optical spectra. It is shown that the experimentally determined symmetry and energy of the Stark sublevels of these multiplets confirm the results of numerical calculations of the energy spectrum of the Tb3+ rare-earth ion in terbium-gallium garnet.

Faraday effect and magnetic susceptibility analyses in TbAlO3

The magnetic susceptibility χ and the Verdet constant V obtained along the crystallographic axis [110] of the rhombic TbAlO3 crystal have been investigated experimentally and theoretically in the temperature range between 78 and 300 K. We find that the Verdet constant V is not a linear function based on the magnetic susceptibility measured along the [110] axis over the same temperature range. It is shown that the temperature dependence of the Verdet constant measured along the [110] axis is associated with the absence of a contribution to the Faraday rotation of the Van Vleck “mixing” of the electronic states of the rare-earth ion Tb3+ that takes place in the presence of an external magnetic field.