Oxygen vacancy and theE1’center in crystallineSiO2

Silica Surface Features and Their Role in the Adsorption of Biomolecules: Computational Modeling and Experiments

“…292,293 For a covalent material like silica, bond cutting brings about the formation of a variety of surface defects, the most relevant being: the Q 3 (•) silyl Si• , the Q 3 (O•) siloxy E' SiO•, the Q 2 (:) >Si: and the Q 2 (O) silanone >Si=O. The nature and stability of these defects has been discussed in the literature [69][70][71][294][295][296][297][298][299][300][301][302][303][304][305] showing that all of them, without exception, are thermodynamically unstable with respect to water hydroxylation. As water is ubiquitously present during biomolecules adsorption these defects should not play an important role in that case.…”

Theory of the structure of the self-trapped exciton in quartz

“…These initial calculations were motivated by the experimental evidence suggesting that the excited state has the structure of a close oxygen-oxygen p i r or peroxy linkage associated with a nearby oxygen vacancy; this evidence includes the similarity of the large uniaxial fine structure to the fine structure of molecular oxygen (Tinkham and Strandberg 1954) and the resemblance of the 5.4 eV a.bsorption line to the 5.8 eV absorption in the oxygen vacancy or E-centre which has been known in quartz for some years (Tanimura et a1 1983, Weeks 1956, Rudra and Fowler 1987. We have reported elsewhere (Fisher et a1 1989, Fisher 1989) some of our calcuhtions designed to test this model; in particular, we found that the fine structure to be expected from an (O,),-molecular ion is similar to that observed in quartz if the interatomic axis is identified with the fine-structure principal axis.…”

Atomic-resolution single-spin magnetic resonance detection concept based on tunneling force microscopy

“…4) E' γ centers have long spin-lattice relation times (T 1 ) of ≈200 µs at room temperature [29,30]. There are many variations of E' γ centers found in amorphous SiO 2 due to the large spread of bond angles and bond lengths found in the amorphous network [31][32][33][34][35]. While the microscopic theory for the E' γ center is not without controversy [36], the common feature among all variations is an unpaired electron on a silicon atom back-bonded to three oxygen atoms, i.e.…”