Triplet states of oxygen vacancy defects in α-quartz: Center E9

The paramagnetic E-9 '' center in triplet state occurring in electron-irradiated, synthetic alpha-quartz has been investigated by using electron paramagnetic resonance (EPR) spectroscopy. The primary spin Hamiltonian parameter matrices g, D and A (hyperfine interactions for five Si-29 nuclei) have now been determined. The principal values and principal directions of D and A matrices allow us to suggest the structural model for this stable triplet defect. The E-9 '' center involves the two unpaired electrons located in the orbitals of two silicon atoms next to one oxygen vacancy each. Firm correlations between the spin Hamiltonian matrix principal axes and crystallographic directions have been attained. Copyright (C) EPLA, 2014