Stable states of E defects in α-quartz

Several new radiation defects in triplet states occurring in electron-irradiated, synthetic alpha-quartz have been observed by using electron paramagnetic resonance (EPR) spectroscopy. These defects are stable at room temperature and above for years. The primary spin Hamiltonian parameter matrices g and D have now been determined for four stable triplet defects, which herein are labeled E-6 '', E-7 '', E-8 '', and E-9 ''. Inter-electron distances estimated by using the magnetic dipole model suggest that the structures of new E '' centers involve the unpaired electrons located in the orbitals of two silicon atoms next to one oxygen vacancy each. Our results suggest that the optical band at 5.67 eV is related to these triplet defects. Copyright (C) EPLA, 2012