Titolo:  Thermodynamic models of the adsorption and desorption of molecular oxygen at the UV and blue emitting centers in mesoporous silica under variable oxygen pressure
Data di pubblicazione:  2017
Data di prima pubblicazione on-line:  2016
Autori:  Carbonaro, Carlo Maria; Salis, Marcello; Corpino, Riccardo; Chiriu, Daniele; Stagi, Luigi; Serra, Giovanni; Bosin, Andrea; Ricci Pier Carlo
Numero degli autori:  8
Lingua:  Inglese
Presenza coautori internazionali:  no
Volume:  239
Pagina iniziale:  371
Pagina finale:  380
Numero di pagine:  10
Digital Object Identifier (DOI):  http://dx.doi.org/10.1016/j.micromeso.2016.10.037
Codice identificativo Scopus:  2-s2.0-84994368003
Codice identificativo ISI:  WOS:000389284300042
Abstract:  The UV excited emission properties of mesoporous silica in the blue and UV range are modified by the adsorption and desorption of oxygen molecules at the two defect sites. To interpret the experimental purging cycles we model the oxygen-silica interaction at thermodynamic level, succeeding in explaining the interaction mechanism and the trend of UV centre to undergo photo-bleaching when excited under vacuum conditions. The analysis called for the presence of two different set of defects for both the centres, pinpointed as defects liable to interact with O2 and non-interacting isolated defects. To support the thermodynamic analysis, we simulated the O2 adsorption and desorption processes within the first principles DFT cluster framework. The calculated atomic configurations and the potential energy curves along selected probable reaction paths allow suggesting the kinetics of molecular oxygen interaction on examined surface silica defects and pointing at an oxygen vacancy E’-like defect as the possible result of the UV centre photo-bleaching.
Parole chiave:  Mesostructured silica; thermodynamic models; adsorption/desorption of oxygen; luminescence
Tipologia: 1.1 Articolo in rivista

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