Spin Hamiltonian Parameters for Co2+ Ions in PbMoO4 Crystal - Interplay between the Fictitious Spin S′=1/ 2 and the Effective Spin (S)over-tilde=3/2

The interplay between the fictitious spin S' = 1/2 and the effective spin (S) over tilde = 3/2 for Co2+(3d 7) ions is considered. The available experimental data on the Ze g'(i) factors for the two Co2+ complexes in PbMoO4 obtained using the fictitious " spin" S' = 1/2 description serve for determination of the Zeeman gi factors corresponding to the effective spin (S) over tilde = 3/2. The second-rank zero-field splitting parameters D and E ((S) over tilde = 3/2) are also indirectly determined from the experimental EMR data by employing the formulas arising from projection of the gi((S) over tilde = 3/2) factors onto the g'(i) (S' = 1/2) factors. The so-determined second-rank zero-field splitting parameters and gi((S) over tilde = 3/2) factors will enable comparison with the respective quantities obtained in a subsequent paper using a combined modeling approach.