An electron nuclear double resonance analysis was made of the S2- defect. A complete angular variation of one set of 85Rb and 87Rb electron nuclear double resonance transitions was measured, and the corresponding hyperfine and nuclear quadrupole coupling tensors were determined. The orientation of the principal axes of these tensors was in good agreement with the overall D2h symmetry of the S2- ion in the lattice. The electron nuclear double resonance results clearly implied a mono-vacancy model in which the S2- ion replaced one I- ion on a lattice site. The line-width of the electron paramagnetic resonance signals could be explained by using the electron nuclear double resonance data. A comparison was made with previous electron nuclear double resonance studies of O2- and S2- defects in Rb halides.

S.Van Doorslaer, F.Callens, F.Maes, P.Matthys: Journal of Physics - Condensed Matter, 1995, 7[48], 9279-86