| Реферат: | eng: Several new radiation defects with total electron spin S = 1 occurring in electron-irradiated, synthetic α-quartz have been observed by using electron paramagnetic resonance spectroscopy. These defects are considered to be biradicals, i. e., pairs of S = 1/2 species. The concentration of these centers depends on the condition of the fast-electron irradiation. They have different decay behaviors that allow measurements of any individual species especially when it predominates over the others. The primary spin Hamiltonian parameter matrices g1, g2, D have now been determined for two similar defects, which herein are labeled. Inter-electron distances estimated by using the magnetic dipole model, suggest that the structures of centers, both involve the unpaired electrons each located in orbitals of two silicon atoms next to a common oxygen vacancy but which have slightly different Si-Si distances at 0.90 and 0.79 nm, respectively. This model is consistent with previous DFT calculations of the triplet configurations with local energetic minima. Observed decay behaviors suggest a transformation of centers, center. These triplet centers in quartz provide new insights into the structures of analogous defects in amorphous silica. © 2011 Springer-Verlag.
|