title: Visible-ultraviolet vibronic emission of silica nanoparticles.
abstract: We report the study of the visible-ultraviolet emission properties and the structural features of silica nanoparticles prepared through a laboratory sol-gel technique. Atomic force microscopy, Raman and Infrared investigations highlighted the 10 nm size, purity and porosity of the obtained nanoparticles. By using time resolved photoluminescence techniques in air and in a vacuum we were able to single out two contributions in the visible emission: the first, stable in both atmospheres, is a typical fast blue band centered around 2.8 eV; the second, only observed in a vacuum around the 3.0-3.5 eV range, is a vibrational progression with two phonon modes at 1370 cm(-1) and 360 cm(-1). By fully characterizing the spectroscopic features of this structured emission, we determine its vibronic properties and clarify the different origins with respect to the blue luminescent defect.
authors.affiliation: Dipartimento di Fisica e Chimica, Università di Palermo, I-90123 Palermo, Italy. marco.cannas@unipa.it.
authors.forename: Luisa
authors.initials: L
authors.lastname: Spallino
authors.forename: Lavinia
authors.initials: L
authors.lastname: Vaccaro
authors.forename: Luisa
authors.initials: L
authors.lastname: Sciortino
authors.forename: Simonpietro
authors.initials: S
authors.lastname: Agnello
authors.forename: Gianpiero
authors.initials: G
authors.lastname: Buscarino
authors.forename: Marco
authors.initials: M
authors.lastname: Cannas
authors.forename: Franco Mario
authors.initials: FM
authors.lastname: Gelardi
mesh_terms: D018625:Microscopy, Atomic Force; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman; D013499:Surface Properties
chemical_list: D012822:Silicon Dioxide