We studied the emission of the O2 molecules embedded in fumed silica (amorphous silicon dioxide) nanoparticles differing for diameters and specific surface. By using a 1064 nm laser as a source we recorded both the O2 emission and the Raman signal of silica. Our experimental data show that the O2 emission/Raman signal (at 800cm-1) ratio decreases with increasing the specific surface both for the as received and the loaded samples. By performing a thermal treatment (600 °C for 2h) we modified the structure and the water content of the smallest nanoparticles without observing any significant change in the O2 emission/Raman signal ratio. Our data are explained by a shell model showing that the O2 emission is essentially due to the molecules entrapped in the core of the nanoparticles, whereas the contribution due to the surface shell, having a thickness of about 1 nm, is negligible because of its high content of Si-OH groups that introduce non-radiative relaxation channels or because of the very low content of molecules trapped in this thin region.

Alessi, A., Iovino, G., Buscarino, G., Agnello, S., Gelardi F M (2013). Entrapping of O2 Molecules in Nanostructured Silica Probed by Photoluminescence. JOURNAL OF PHYSICAL CHEMISTRY. C, 117(6), 2616-2622 [10.1021/jp310314t].

Entrapping of O2 Molecules in Nanostructured Silica Probed by Photoluminescence

ALESSI, Antonino;IOVINO, Giuseppe;BUSCARINO, Gianpiero;AGNELLO, Simonpietro;GELARDI, Franco Mario
2013-01-01

Abstract

We studied the emission of the O2 molecules embedded in fumed silica (amorphous silicon dioxide) nanoparticles differing for diameters and specific surface. By using a 1064 nm laser as a source we recorded both the O2 emission and the Raman signal of silica. Our experimental data show that the O2 emission/Raman signal (at 800cm-1) ratio decreases with increasing the specific surface both for the as received and the loaded samples. By performing a thermal treatment (600 °C for 2h) we modified the structure and the water content of the smallest nanoparticles without observing any significant change in the O2 emission/Raman signal ratio. Our data are explained by a shell model showing that the O2 emission is essentially due to the molecules entrapped in the core of the nanoparticles, whereas the contribution due to the surface shell, having a thickness of about 1 nm, is negligible because of its high content of Si-OH groups that introduce non-radiative relaxation channels or because of the very low content of molecules trapped in this thin region.
Alessi, A., Iovino, G., Buscarino, G., Agnello, S., Gelardi F M (2013). Entrapping of O2 Molecules in Nanostructured Silica Probed by Photoluminescence. JOURNAL OF PHYSICAL CHEMISTRY. C, 117(6), 2616-2622 [10.1021/jp310314t].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/70443
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