It means that the relative sharp lines could be expected in the absorption or excitation spectrum, which is the criterion for assignments of levels for Mn2+ ion. Since all the excited states of Mn2+ ion (3d5) would either be quartets or doublets, the optical absorption spectra of Mn2+ ion-doped materials have only spin forbidden transitions [17,18]. In octahedral co-ordination, Co2+ free ion ground state 4F splits into the 4T1, 4T2 and 4A2 states with the 4T1 state as the lowest.