Search results for " Dangling bonds"
showing 2 items of 2 documents
Experimental evidence for two different precursors of E’γ centers in silica
2004
Electron paramagnetic resonance measurements of concentration and line shape of centers induced by γ ray irradiation are presented for natural and synthetic commercial silica with different OH contents. Synthetic materials with OH content >200 ppm by weight show one line shape for all investigated doses. In contrast, the other materials show a different line shape at low irradiation doses. Differences are also observed in the concentration growth of the centers in synthetic wet materials and in the other materials. The results are interpreted as evidence of two centers distinguishable by their line shape and having different precursors.
Luminescence of non-bridging oxygen hole centers as a marker of particle irradiation of {\alpha}-quartz
2021
The origin of the "red" emission bands in the 600 nm-700 nm region, observed in quartz crystals used for luminescence dating and environmental dosimetry, is still controversial. Their reported spectral and lifetime characteristics are often similar to those of oxygen dangling bonds ("non-bridging oxygen hole centers, NBOHCs") in glassy silicon dioxide. The presence of these "surface radical type" centers in quartz crystal requires sites with highly disordered local structure forming nano-voids characteristic to the structure of glassy SiO2. Such sites are introduced in the tracks of nuclear particles ({\alpha}-irradiation, neutrons, ions). In case of electrons they are created only at large…