Hamiltonian of crystalline field in an approximation of strong configuration interaction

Modified theory of f-f transition intensities and crystal field for systems with anomalously strong configuration interaction

“…In this theory the anomalous strong interaction between some multiplets with ligands of the nearest environment is taken into account. The existing theories [1][2][3][4][5] give poor agreement between the calculated and experimental luminescence branching ratios for Pr 3+ ion in double molybdates. The absorption and emission transitions of Pr 3+ ion in double molybdates was chosen as the first application of the new theory and has provided, for the first time, a satisfactory description of the experimental data [6] for this system.…”

“…However, for systems with strong configuration interactions, such as Am 3+ ions in fluorozirconate glass [13] or BrCl 6 :U 4+ [14], expression (2) can not provide a satisfactory description of the intensity of absorption transitions, and an approximation of a strong configuration interaction [4,5] is more adequate.…”

“…The reason behind this failure is that expression (3) can be derived if the determinant contribution to the line strength of the transition is given either by only one excited configuration, or by several excited configurations with similar energy, ∆. To take the influence of several excited configurations with different energies, ∆ , into account, we shall use expression (12) of [4] for the effective operator of electric dipole moment, D :…”

“…It is well-known that the application of the Judd-Ofelt method [1,2] often fails to provide a correct description for the absorption transitions. Application of the modified theories [3][4][5] al-lows one to improve the description of the intensity of the absorption transitions considerably. However for some systems, for example that of the Pr 3+ ion in M + Bi(XO 4 ) 2 , M + = Li, Na and X=W, Mo [6], it is not possible to achieve a satisfactory description of the intensities of both the absorption and luminescent transitions simultaneously within the framework of these theories.…”

“…The reason a simultaneous description can not be achieved is due to the significant influence of excited configurations on the intensity of the absorption and luminescent transitions; then smaller the energy gap between the excited configuration and the Pr 3+ multiplet is the greater its influence. The influence of excited configurations on intensities of the intermultiplet transitions is taken into account by modified theories [3][4][5] but not sufficiently. The development of improved laser materials to meet many practical applications is an active area of research, and this area of work has produced considerable experimental data on the intensities of the absorption and luminescent transitions [7][8][9] which can not be satisfactorily described within the framework of existing theories [1][2][3][4][5].…”