Experimental definition of Zeeman splitting of excited states of Tb3+ ion in Y3Al5O12

The energy spectrum of the F-7(3) multiplet of a Tb3+ ion in one of the non -equivalent positions (of D-2 symmetry) occupied by a rare-earth ion in the Y3Al5O12 crystallographic garnet structure is calculated. The energy spect rum of the F-7(3) state is characterized by the presence of quasi-doublet s tates formed by closely located Stark singlet states, that are effectively "mixed" in an external magnet field H. This inference is seriously confirme d by results of experimental studies of magneto-polarized luminescence on t he radiative D-5(4) --> F-7(3) 4f-4f transition in Y3Al5O12:Tb3+. The optic al transitions are identified, and the components of the g-factor of the F- 7(3)(Gamma(2), Gamma(4)) quasi-doublets in the Y3Al5O12 structure are deter mined.