Analysis of (⁷F₀)Γ_1g→ (⁵D₂)Γ_5g, Γ_3gand (⁷F₀)Γ_1g→(⁵L₆)Γ_1g, aΓ_5gtwo-photon absorption spectra of Cs₂NaYF₆:Eu³⁺

Abstract

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) Γ1g→(5D2)Γ5g, Γ3g 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)Γ1g→(5L6)Γ1g, aΓ5g transitions, serious discrepancies between experiment and theory are found if the intermediate states are constructed from a 4f5 core comprising free ion states and the 5d1 crystal field states. Satisfactory agreement is, however, found when the 4f5 crystal field states are utilized in constructing the intermediate states. The contributions to the transition moment have been evaluated for various Hamiltonian terms and the results are discussed.

Crystal-field analysis and calculation of two-photon absorption line strengths of dicesium sodium hexachlorogadolinate(III)

“…The summation over TPA virtual states was taken explicitly over all the obtained 4f 6 5d states by following [5]. This is in contrast to calculations based on perturbation expansion [2,3,15], and calculations based on neglecting fd interactions [16].…”