0000000000162582

AUTHOR

Dan Sporea

showing 7 related works from this author

Structure of amorphous SiO 2 nanoparticles probed through the E′ γ centers

2011

We report an experimental investigation by electron paramagnetic resonance (EPR) spectroscopy on the properties of the E′ γ centers induced by β-ray irradiation in nanoparticles of amorphous SiO 2 (fumed silica) with mean diameters from 7 up to 40 nm. We found that the E′ γ centers are induced in all the fumed silica types in the dose range 4-400 kGy. They are characterized by an EPR line shape similar to that observed in common bulk silica materials independently on the particle diameter. Moreover, the E′ γ center concentration decreases on decreasing of the particle size for each given dose. Our findings are interpreted in terms of a shell-like model of nanoparticles in which it is assume…

Materials scienceElectronic Optical and Magnetic MaterialSettore FIS/01 - Fisica SperimentaleAnalytical chemistryNanoparticleSurfaces Coatings and FilmNanotechnologySurfaces Coatings and FilmsElectronic Optical and Magnetic Materialslaw.inventionAmorphous solidGeneral EnergyEnergy (all)lawParticle sizeIrradiationPhysical and Theoretical ChemistryElectron paramagnetic resonanceSpectroscopypoint defects silica nanoparticles electron paramagnetic resonanceRadiation resistanceFumed silica
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<title>Study of color centers in optical fibers to be used for ITER plasma diagnostics</title>

2007

ABSTRACT The paper presents a comparative study, by off-line measurements of the irradiation induced optical attenuation in several large diameter (600 µm) optical fibers subjected to gamma-rays and neutron irradiation. The optical fiber samples fall into two categories: optical fibers with an enhanced UV transmission (high OH content core) and solarization resistant optical fibers. The irradiation conditions were as follows: a) gamma irradiation at a 60 Co source, with a dose rate of 0.33 kGy/h +/- 5%, up to the maximum total irradiation dose of 313 kGy; b) neutron irradiation (mean energy 5.2 MeV) using a deuteron beam (13 MeV) and a thick beryllium target, for a total fluence of 6x10 12 …

Optical fibergenetic structuresPhysics::Instrumentation and DetectorsChemistryAstrophysics::High Energy Astrophysical PhenomenaAttenuationPhysics::Medical PhysicsRadiochemistryNear-field opticsPhysics::Opticschemistry.chemical_elementRadiationFluenceeye diseaseslaw.inventionlawAstrophysics::Earth and Planetary AstrophysicsIrradiationBerylliumElectron paramagnetic resonanceSPIE Proceedings
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Evaluation of the UV Optical Transmission Degradation of Gamma-ray Irradiated Optical Fibers

2007

This paper highlights our recent results on the investigation of the transmission attenuation in the UV spectral range induced by gamma-ray irradiation of optical fibers, and the comparison with results obtained by electron paramagnetic resonance (EPR) and photoluminescence measurements.

Materials sciencePhotoluminescenceOptical fiberbusiness.industryAstrophysics::High Energy Astrophysical PhenomenaAttenuationGamma rayPhysics::OpticsResonancelaw.inventionCondensed Matter::Materials ScienceOpticslawOptoelectronicsIrradiationbusinessElectron paramagnetic resonanceSpectroscopy2007 Conference on Lasers and Electro-Optics - Pacific Rim
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Comparison of γ and β-ray irradiation effects in sol-gel Ge-doped SiO<inf>2</inf>

2009

We report an experimental study on the comparison between the γ or β ray induced Ge related point defects in Ge doped silica. Silica samples doped with ∼2.2 1017 Ge atoms/cm3 produced with the sol-gel technique have been irradiated. The effects of the irradiation have been investigated by optical absorption, photoluminescence and electron paramagnetic resonance spectroscopy in order to evaluate the generation and the dependence on dose of the Ge(1), E'Ge, Germanium Lone Pair Center (GLPC) and H(II) point defects. No relevant differences between the concentrations of γ or β ray induced Ge(1) and E'Ge point defects have been observed. In addition, it is found that both irradiations are able t…

PhotoluminescenceMaterials sciencebusiness.industryDopingInfrared spectroscopychemistry.chemical_elementGermaniumCrystallographic defectchemistryPhysical chemistryOptoelectronicsIrradiationbusinessSpectroscopyLone pair2009 European Conference on Radiation and Its Effects on Components and Systems
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Formation of optically active oxygen deficient centers in Ge-doped SiO2 by γ- and β-ray irradiation

2010

Abstract We report an experimental study on the comparison between the γ- or β-ray induced Ge related point defects in Ge-doped silica. Silica samples doped with ∼2.2 1017 Ge atoms/cm3 produced with the sol–gel technique have been irradiated with γ-ray or with β-ray. The effects of the irradiation have been investigated by optical absorption, photoluminescence and electron paramagnetic resonance spectroscopy in order to evaluate the generation and the dependence on dose of the Ge(1), E’Ge, GLPC (Germanium lone pair center) and H(II) point defects. No relevant differences between the concentrations of γ- or β-ray induced Ge(1) and E’Ge point defects have been observed and, in addition, it ha…

PhotoluminescenceAbsorption spectroscopySettore FIS/01 - Fisica Sperimentalechemistry.chemical_elementGermaniumdifetti di punto in siliceCondensed Matter PhysicsCrystallographic defectElectronic Optical and Magnetic Materialslaw.inventionCrystallographychemistrylawMaterials ChemistryCeramics and CompositesIrradiationSpectroscopyElectron paramagnetic resonanceLone pairNuclear chemistryJournal of Non-Crystalline Solids
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Sun-Induced Chlorophyll Fluorescence I: Instrumental Considerations for Proximal Spectroradiometers

2019

Growing interest in the proximal sensing of sun-induced chlorophyll fluorescence (SIF) has been boosted by space-based retrievals and up-coming missions such as the FLuorescence EXplorer (FLEX). The European COST Action ES1309 “Innovative optical tools for proximal sensing of ecophysiological processes” (OPTIMISE, ES1309; https://optimise.dcs.aber.ac.uk/) has produced three manuscripts addressing the main current challenges in this field. This article provides a framework to model the impact of different instrument noise and bias on the retrieval of SIF; and to assess uncertainty requirements for the calibration and characterization of state-of-the-art SIF-oriented spectroradiom…

010504 meteorology & atmospheric sciencesUFSP13-8 Global Change and BiodiversitySensor model0211 other engineering and technologiesEarth and Planetary Sciences(all)02 engineering and technology01 natural sciencesErrorsensor modelSpectroradiometerSun-induced chlorophyll fluorescencesun-induced chlorophyll fluorescence; spectroradiometer; sensor model; uncertainty; errorCalibrationCost actionuncertaintylcsh:ScienceChlorophyll fluorescencesun-induced chlorophyll fluorescence/dk/atira/pure/subjectarea/asjc/1900021101 geological & geomatics engineering0105 earth and related environmental sciencesRemote sensingNoise (signal processing)1900 General Earth and Planetary SciencesUncertaintySensor modelReflectivityerror3. Good healthValidation methodsSpectroradiometerspectroradiometerEnvironmental science570 Life sciences; biologyGeneral Earth and Planetary Scienceslcsh:QRemote Sensing
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Alpha and deuteron irradiation effects on silica nanoparticles

2014

We present an experimental investigation focused on the effects of alpha and deuteron irradiation on different silica nanoparticles. The study has been devoted also to characterize the induced point defects and the eventual structural modifications to evaluate the effects of the different irradiation source in comparison with the bulk materials. After irradiation up to about 10^16 ions cm^-2, we performed electron paramagnetic resonance (EPR), photoluminescence (PL), infrared (IR) absorption, Raman, and atomic force microscopy (AFM) measurements. We found that the two types of irradiation qualitatively induce comparable effects. Furthermore, irradiation generates the socalled twofold coordi…

PhotoluminescenceMaterials scienceMechanical EngineeringSettore FIS/01 - Fisica SperimentaleNanoparticlePhotochemistryFluenceCrystallographic defectlaw.inventionIonsymbols.namesakeNuclear magnetic resonanceMechanics of MaterialslawsymbolsNanoparticles irradiationGeneral Materials ScienceIrradiationRaman spectroscopyElectron paramagnetic resonance
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