Analysis of ( 7 F 0 )Γ 1g → ( 5 D 2 )Γ 5g , Γ 3g and ( 7 F 0 )Γ 1g →( 5 L 6 )Γ 1g , aΓ 5g two-photon absorption spectra of Cs 2 NaYF 6 :Eu 3+ (original) (raw)
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Third-order contributions to the 8 S 7/2 6 P 7/2 , 6 P 5/2 two-photon transitions of Eu 2+ in KMgF 3
Journal of Physics: Condensed Matter, 2004
The direct calculation of transition line strengths and relative intensities is presented for two intraconfigurational two-photon absorption (TPA) transitions of Eu 3+ in the cubic Cs 2 NaYF 6 host. Crystal field wavefunctions were utilized for the initial and final f N -electron states and various approaches were used in constructing all the 4f N −1 5d 1 intermediate-state wavefunctions. The calculated relative intensities of the ( 7 F 0 ) 1g → ( 5 D 2 ) 5g , 3g TPA transitions are in reasonable agreement with experiment. The neglect of J -mixing in the initial state has only a small effect upon the calculation, whereas the neglect of spinorbit couplings within the initial and terminal states drastically reduces the calculated transition linestrengths, but does not markedly change the intensity ratios. In the case of the ( 7 F 0 ) 1g → ( 5 L 6 ) 1g , a 5g transitions, serious discrepancies between experiment and theory are found if the intermediate states are constructed from a 4f 5 core comprising free ion states and the 5d 1 crystal field states. Satisfactory agreement is, however, found when the 4f 5 crystal field states are utilized in constructing the intermediate states.
The direct calculation of transition line strengths and relative intensities is presented for two intraconfigurational two-photon absorption (TPA) transitions of Eu3+ in the cubic Cs2NaYF6 host. Crystal field wavefunctions were utilized for the initial and final fN-electron states and various approaches were used in constructing all the 4fN-1 5d1 intermediate-state wavefunctions. The calculated relative intensities of the (7F0) Gamma1g-->(5D2)Gamma5g, Gamma3g TPA transitions are in reasonable agreement with experiment. The neglect of J-mixing in the initial state has only a small effect upon the calculation, whereas the neglect of spin-orbit couplings within the initial and terminal states drastically reduces the calculated transition linestrengths, but does not markedly change the intensity ratios. In the case of the (7F0)Gamma1g-->(5L6)Gamma1g, aGamma5g transitions, serious discrepancies between experiment and theory are found if the intermediate states are constructed from ...
Third-order contributions to the 7 F 0 5 D 2 two-photon transition of Eu 3 in a cubic lattice
Journal of Physics: Condensed Matter, 2002
The direct calculation of transition line strengths and relative intensities is presented for two intraconfigurational two-photon absorption (TPA) transitions of Eu 3+ in the cubic Cs 2 NaYF 6 host. Crystal field wavefunctions were utilized for the initial and final f N -electron states and various approaches were used in constructing all the 4f N −1 5d 1 intermediate-state wavefunctions. The calculated relative intensities of the ( 7 F 0 ) 1g → ( 5 D 2 ) 5g , 3g TPA transitions are in reasonable agreement with experiment. The neglect of J -mixing in the initial state has only a small effect upon the calculation, whereas the neglect of spinorbit couplings within the initial and terminal states drastically reduces the calculated transition linestrengths, but does not markedly change the intensity ratios. In the case of the ( 7 F 0 ) 1g → ( 5 L 6 ) 1g , a 5g transitions, serious discrepancies between experiment and theory are found if the intermediate states are constructed from a 4f 5 core comprising free ion states and the 5d 1 crystal field states. Satisfactory agreement is, however, found when the 4f 5 crystal field states are utilized in constructing the intermediate states.
Direct calculation of lanthanide optical transition intensities Nd 3+:YAG
Journal of Alloys and Compounds, 1995
The influence of Coulomb and spin-orbit interactions on one-photon transitions within the 4f3 configuration of Nd3+ in YAG is taken into account by a “direct” calculation, which explicitly evaluates the eigenstates of 4f3 and 4f25d. The interconfigurational crystal-field parameters are fitted to the experimental data and the traditional one-electron intensity parameters are retained to account for non-crystal-field mechanisms. A small but significant improvement in the fit is obtained.
Chinese Physics B, 2009
The spin-orbit interaction of 5d electron needs to be taken into account to give proper energy structure for 4f N −1 5d configuration of heavy lanthanide ions occupying a site with ligands forming an octahedron. This paper derives the theoretical results for the energy structure by treating the t 2 orbitals as quasi p orbitals and then using angular-momentum coupling techniques. An analytic expression for the electric dipole absorption line strengths between 4f N multiplets and 4f N −1 5d states is given in terms of various angular-momentum quantum numbers and re-coupling coefficients. The result is then applied to interprete the excitation spectrum of Cs 2 NaYF 6 :Er 3+ . The high-spin and lowspin states of Cs 2 NaYF 6 :Er 3+ are discussed in terms of the wavefunctions obtained by using the developed theoretical model.
Journal of Luminescence, 2014
Wavefunction-based ab-initio calculations of the electric-dipole moments of 4f N -4f N transitions of lanthanide ions are performed to extract the A λ tp intensity parameters. The extraction method is an extension of our earlier calculations of crystal-field (CF) parameters for lanthanide ions in crystals. The CASSCF/RASSI-SO (Complete-Active-Space Self-Consistent-Field/Restricted-Active-Space State-Interaction Spin-Orbit) calculations have been carried out on the chosen model system of CaF 2 : Ce 3 þ with an interstitial fluoride ion (F À i ) on z-axis (Ce 3 þ ion occupying the C 4v symmetry site). In consideration of the site symmetry and the coordination situation of Ce 3 þ ion at C 4v site in CaF 2 as well as the superposition model (SM), the calculated intensity parameters for Ce 3 þ ion can be classified into three categories, and detailed discussions are then given.
Extraction of crystal-field parameters for lanthanide ions from quantum-chemical calculations
Journal of Physics: Condensed Matter, 2011
A simple method for constructing effective Hamiltonians for the 4f N and 4f N-1 5d energy levels of lanthanide ions in crystals from quantum-chemical calculations is presented. The method is demonstrated by deriving crystal-field and spin-orbit parameters for Ce 3+ ions doped in LiYF 4 , Cs 2 NaYCl 6 , CaF 2 , KY 3 F 10 and YAG host crystals from quantum chemical calculations based on the DV-Xα method. Good agreement between calculated and fitted values of the crystal-field parameters is obtained. The method can be used to calculate parameters even for low-symmetry sites where there are more parameters than energy levels.
Spectroscopy and Calculations for 4f N → 4f N –1 5d Transitions of Lanthanide Ions in K 3 YF 6
The Journal of Physical Chemistry A, 2012
In the present work, we report on the combined experimental and theoretical studies of the 4f−5d spectra of Ce 3+ , Pr 3+ , Nd 3+ , Eu 3+ , Gd 3+ , Tb 3+ , Dy 3+ , and Er 3+ ions in a newly synthesized K 3 YF 6 matrix. The low temperature experimental 4f−5d excitation spectra have been analyzed and compared with the results of the energy-level and intensity calculations. For this theoretical analysis, the extended phenomenological crystal-field model for the 4f N−1 5d configuration (i.e., the extended f-shell programs, developed by Prof. M. F. Reid) and exchange charge model (developed by Prof. B. Z. Malkin) have been used together to estimate the crystal field parameters and implement the spectral simulations. On the basis of the results of the performed theoretical analysis, we suggest the most probable positions occupied by optically active ions. Although the spectra of only eight lanthanide ions have been studied, the Hamiltonian parameters of the 4f N−1 5d configuration have been evaluated for the whole lanthanide series and reported here for the first time, to give a complete and unified description of the spectroscopic properties of the trivalent rare earth ions in the chosen host. In addition to the studies of the 4f−5d transitions, various possible competitive excitation channels overlapping with 4f−5d ones have also been discussed, where a theoretical scheme giving rudiments to understand 4f−6s spectra are proposed for the first time. An excellent agreement between the calculated and measured excitation spectra shapes confirms validity of the performed analysis. The obtained parameters of the crystal field Hamiltonians for different ions and various electron configurations can be used in a straightforward way to generate the energy level positions and calculate the particular transition intensities for any rare earth ion in any particular spectral region. With the aid of the obtained parameters, the positions of the lowest energy levels of the 4f N , 4f N−1 5d ,and 4f N−1 6s configurations of rare earth ions and 4f N+1 (np) 5 configuration of rare earth ions and ligands (corresponding to the ligand−impurity ion charge transfer transitions) in the band gap of K 3 YF 6 have all been estimated. The obtained Hamiltonian parameters and energy levels diagrams, which include the electronic structure of a host material, can be used as a starting point for analysis of spectroscopic properties of trivalent lanthanides in similar fluorides.