We report an experimental investigation by electron paramagnetic resonance (EPR) on methyl radical (CH3 • ) observed in γ-ray irradiated high-purity amorphous silicon dioxide (a-SiO2) and in a polycrystalline sample of Melanophlogite, a rare natural form of SiO2-clathrate. From the analysis of the EPR spectra we estimate the correlation time of the hindered rotational motion of CH3 • molecules at T=77 K in the two different materials. This physical quantity gives a quantitative measure of the freedom of motion of CH3 • molecules trapped in the two solid systems, putting forward relevant information on the properties of the cavities/interstices inwhich the radicals are confined. In particular, our data suggest that in a-SiO2 the CH3 • molecules are trapped in interstices with diameter significantly lower than about 5.7 Å, which is the size of the smaller cavity involved in the crystalline structure of Melanophlogite.
|Data di pubblicazione:||2013|
|Titolo:||Properties of methyl radical trapped in amorphous SiO2 and in natural SiO2-clathrate Melanoflogite|
|Citazione:||Buscarino, G., Agnello, S., Gelardi, F., & Boscaino, R. (2013). Properties of methyl radical trapped in amorphous SiO2 and in natural SiO2-clathrate Melanoflogite. JOURNAL OF NON-CRYSTALLINE SOLIDS, 361, 9-12.|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1016/j.jnoncrysol.2012.10.034|
|Appare nelle tipologie:||1.01 Articolo in rivista|