Search results for " Luminescence"
showing 10 items of 159 documents
Photosensitivity of SiO2–Al and SiO2–Na glasses under ArF (193 nm) laser
2009
Abstract Photosensitivity of SiO 2 –Al and SiO 2 –Na glass samples was probed by means of the induced optical absorption and luminescence as well as by electron spin-resonance (ESR) after irradiation with excimer-laser photons (ArF, 193 nm). Permanent visible darkening in the case of SiO 2 –Al and transient, life time about one hour, visible darkening in the case of SiO 2 –Na was found under irradiation at 290 K. No darkening was observed at 80 K for either kind of material. This investigation is dedicated to revealing the electronic processes responsible for photosensitivity at 290 and 80 K. The photosensitivity of both materials is related to impurity defects excited directly in the case …
Luminescence of GeO2 glass, rutile-like and α-quartz-like crystals
2006
Abstract The luminescence of GeO 2 rutile-like crystals was studied. Crystals were grown from a melt of germanium dioxide and sodium bicarbonate mixture. Luminescence of the crystal was compared with that of sodium germanate glasses produced in reduced and oxidized conditions. A luminescence band at 2.3 eV was observed under N 2 laser (337 nm). At higher excitation photon energies and X-ray excitation an additional band at 3 eV appears in luminescence. The band at 2.3 eV possesses intra-center decay time constant about 100 μs at 290 K and about 200 μs at low temperature. Analogous luminescence was obtained in reduced sodium germanate glasses. No luminescence was observed in oxidized glasses…
Luminescence properties of AlN nanostructures revealed under UV light irradiation
2007
The luminescence properties of the AlN nanostructures – nanorods and nanotips -revealed under the UV irradiation are similar to those of the AlN ceramics. Presumably they are induced by the recombination processes in the oxygen-related centers. All the studied luminescence processes (photoluminescence, thermoluminescence and optically stimulated luminescence) in the nanostructures occur mainly through the host lattice excitation. That may be explained by the smaller concentration of the defect centers and more perfect structure of the host lattice of the nanostructures compared to the ceramics. The small mutual differences revealed in the spectra and TL curves of the AlN nanotips and nanoro…
Historical mortar: luminescence from fine grain quartz
2010
Within the framework of a research programme aimed at the chronological reconstruction of the structures belonging to the architectonic complex of San Francesco alla Collina of Paternò (Catania, Italy), a procedure was carried out using thermoluminescence (TL) and optically stimulated luminescence (OSL) dating, respectively on terracotta bricks and mortar from the same sampling points. The primary methodological aim was to extend the application of luminescence dating techniques to mortar from historical buildings. Because the TL dating method dates the last firing of bricks, it offers a terminus post quem: the results give the period in which they were manufactured. The possibility that th…
Nano-Oxides produced by ns laser ablation in liquids
2014
Laser ablation in liquids was successfully applied to produce nanosized oxides from Si, Ti and Zn targets. The obtained colloidal solutions of nanoparticles were investigated by complementary techniques: AFM, IR and Raman spectroscopies; optical absorption and time resolved photoluminescence. The results demonstrate the production of SiO2, TiO2 and ZnO. The absorption and emission properties of these material have been also investigated and appear to be promising for optical applications.
Génération et détection d'électrons chauds dans des dispositifs plasmoniques
2021
Hot carrier-based devices are quite promissing for ultrafast photodetection and toset off enhanced physicochemical reactions. Controlling their generation at the nanoscale within plasmonic devices is a key for the future development of hybrid hot carriers technologies. Indeed, Surface PlasmonPolaritons (SPPs) can be exploited to confine light and enhance the number of excited hot carriers. We aim at studying the excitation and dynamics of hot carriers, enhanced by plasmonics, with two different approaches.In a first approach, we aim at controlling the delocalized generation of hot carriers by a propagative SPP. A plasmonic waveguide with a grating coupler is employed. Hot electrons are indi…
Structural and luminescence properties of amorphous SiO2 nanoparticles
2011
We report an experimental study on the photoluminescence band peaked at 2.7 eV (blue band) induced by thermal treatments in nanometric amorphous SiO 2. In particular the emission dependence on the nanometric particles size as a function of their mean diameter from 7 nm up to 40 nm is investigated. We found that the emission amplitude increases on decreasing the particle diameter, showing a strong correlation between the blue band and the nanometric nature of the particles. By Raman spectroscopy measurements it is evidenced that the SiO2 nanoparticles matrix is significantly affected by the reduction of size. Basing on the shell-like model, these findings are interpreted assuming that the de…
Wide range excitation of visible luminescence in nanosilica
2010
The visible luminescence of nanometer-sized silica particles (7 nm mean diameter) was investigated using time resolved spectroscopy. This luminescence is characterized by a wide excitation in the visible and ultraviolet range. The emission spectrum is centred at 2.72 eV with a full width at half maximum of 0.70 eV when excited above 3.5 eV, whereas it progressively empties on the high energy side when excited below 3.5 eV. Moreover, the lifetime falls in the ns timescale and decreases on increasing the emission energy. These features are due to the exceptionally broad inhomogeneous distribution of the emitting centres peculiar to the silica nanoparticles. © 2010 Elsevier B.V. All rights res…
High resolution luminescence spectroscopy and thermoluminescence of different size LaPO4:Eu3+ nanoparticles
2018
T. G. acknowledges the ERDF PostDoc project No. 1.1.1.2/VIAA/1/16/215 (1.1.1.2/16/I/001). K. S. and K. L. acknowledge the Latvian National Research Program IMIS2. The authors from Vinča Institute of Nuclear Sciences acknowledge the financial support of the Ministry of Education, Science and Technological Development of the Republic of Serbia (Project No: 45020 and 172056 ).
Luminescence of X-ray induced radiation defects in modified lithium orthosilicate pebbles with additions of titanium dioxide
2017
The authors greatly acknowledge the technical and experimental support of O. Leys, M. H. H. Kolb, and R. Knitter (Karlsruhe Institute of Technology, Germany). The work is performed in the frames of the University of Latvia financed project No. Y9-B044-ZF-N-300, “Nano, Quantum Technologies, and Innovative Materials for Economics”.