We investigated the red luminescence in a porous film of silica nanoparticles, originating from surface nonbridging oxygen hole centers. The excitation spectrum was measured from 1.8 to 8.0 eV by a tunable laser system and a synchrotron radiation source; this spectrum evidences a peak at 2.0 eV, nearly overlapping withthe emission, and an ultraviolet broadband with peaks at 4.8 and 6.0 eV. The emission is characterized by a spectrum with two subbands split by 0.07 eV, its decay occurs with lifetime longer than 30 microsec and undergoesa thermal quenching by a factor aboout 2 with increasing temperature from 10 to 290 K. The optical characteristics of surface and bulk centers are discussed on the basis of the reported experimental results and quantumchemical calculations.
|Numero di pagine||6|
|Rivista||PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS|
|Stato di pubblicazione||Published - 2008|
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