Many-body perturbation theory for spin-forbidden two-photon spectroscopy of f-element compounds and its application to Eu2+ in CaF2
Predictions of the two-photon transition intensities for Eu2+ in CaF2 generally give poor agreement with experiment because the low-lying excited states make a straightforward application of perturbation theory unreliable. In this work we explicitly include the effective Coulomb interaction and the crystal-field interaction for the excited configuration in the zeroth-order Hamiltonian, and treat the spin-orbit interaction as a perturbation. We obtain a good agreement with measured multiplet to multiplet two-photon absorption intensities. The linewidths of the two-photon absorption peaks, which vary dramatically, are explained by selection rules for nonradiative relaxation.
Physical Review B
Duan, C.; Reid, M.; and Burdick, Gary, "Many-body perturbation theory for spin-forbidden two-photon spectroscopy of f-element compounds and its application to Eu2+ in CaF2" (2002). Faculty Publications. 54.