STRONGLY PERTURBED NEGATIVE-VACANCY-RELATED CENTERS IN DIAMOND

Several related defect centers have been observed in synthetic and typ e-Ib diamond following electron or neutron irradiation. Such centers, termed W centers, have similar characteristic features in that all hav e a spin of S = 3/2 and exhibit an extremely large zero-field splittin g. Spin-Hamiltonian parameters have been determined which describe the EPR results and characterize the defects. The origin of the zero-fiel d splitting at such centers is discussed within a distorted-negative-v acancy model in which the zero-field splitting is associated with mixi ng of negative-vacancy molecular states through a spin-orbit interacti on. It is concluded that W centers are associated with negative vacanc ies that have been extensively distorted.