Search results for "purity"

showing 10 items of 356 documents

Ab Initio Calculations of Hydroxyl Impurities in CaF2

2012

OH– in CaF2 crystal and the (111) surface have been studied by using density functional theory (DFT) with hybrid exchange potentials, namely, DFT-B3PW. Three bulk and 20 surface OH– configurations ...

Surface (mathematics)CrystalGeneral EnergyChemistryComputational chemistryImpurityAb initio quantum chemistry methodsPhysical chemistryDensity functional theoryPhysical and Theoretical ChemistrySurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsThe Journal of Physical Chemistry C
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Optical quenching and recovery of photoconductivity in single-crystal diamond

2017

We study the photocurrent induced by pulsed-light illumination (pulse duration is several nanoseconds) of single-crystal diamond containing nitrogen impurities. Application of additional continuous-wave light of the same wavelength quenches pulsed photocurrent. Characterization of the optically quenched photocurrent and its recovery is important for the development of diamond based electronics and sensing. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license. This work was supported by AFOSR and the DARPA QuASAR program, by NSF Grant No. ECCS-1202258, and by DFG through the DIP program (FO 703/2-1).

TechnologyPhysics and Astronomy (miscellaneous)FOS: Physical sciencesPhysics::Optics02 engineering and technologyengineering.material01 natural sciencesEngineeringOpticsImpuritycond-mat.mes-hall0103 physical sciencesMesoscale and Nanoscale Physics (cond-mat.mes-hall)010306 general physicsApplied PhysicsPhotocurrentPhysicsQuenchingCondensed Matter - Mesoscale and Nanoscale Physicsbusiness.industryCondensed Matter::OtherPhotoconductivityDiamondPulse durationQuantum PhysicsNanosecond021001 nanoscience & nanotechnologyCondensed Matter::Mesoscopic Systems and Quantum Hall EffectWavelengthPhysical SciencesengineeringOptoelectronicsphysics.optics0210 nano-technologybusinessOptics (physics.optics)Physics - Optics
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Rapid and eco-friendly synthesis of graphene oxide-silica nanohybrids

2014

The increasing interest in Graphene oxide (GO) is due to many issues: the presence of both sp2-conjugated atoms and oxygen-containing functional groups provides a strong hydrophilicity and the possibility to further functionalize it with other molecules (i.e. π-π interactions covalent attachment etc.) [1]. Furthermore since the GO is biocompatible and noncytotoxic many studies have been recently focused on the development of GO-based nanodevices for bioimaging DNA detection drug delivery. Due to their low cytotoxicity and large internal surface area silica nanoparticles have been taken into account as promising material for biolabeling and drug loading/delivery. Particular consideration has recently been demonstrated for GO-silica composites because of the potentialities for electrical applications their chemical inertia and stability toward ions exposure. The possibility to combine the extraordinary properties of GO and silica offers several advantages for the realization of nanoprobes for biological applications and of biosensor [12]. The strategy for the fabrication of GO-nanosilica nanohybrids can be schematized as follows: (i) synthesis of GO by oxidizing graphite powder with the method described by Marcano et al. [3] (ii) Preparation of oxygen-loaded silica nanoparticles by thermal treatments in controlled atmosphere in order to induce high NIR emission at 1272 nm from high purity silica nanoparticles. (iii) preparation of GrO-silica nanohybrid films via rapid solvent casting in water. The nanohybrids were tested by XPS FTIR Raman analysis UV photoluminescence analysis TGA Zeta potential measurements electrical tests AFM and SEM. Several nanohybrids were prepared by combining two different typologies of GO and two different samples of silica.
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Hydrogen and Deuterium Incorporation in ZnO Films Grown by Atomic Layer Deposition

2021

Zinc oxide (ZnO) thin films were grown by atomic layer deposition using diethylzinc (DEZ) and water. In addition to depositions with normal water, heavy water (2H2O) was used in order to study the reaction mechanisms and the hydrogen incorporation at different deposition temperatures from 30 to 200 °C. The total hydrogen concentration in the films was found to increase as the deposition temperature decreased. When the deposition temperature decreased close to room temperature, the main source of impurity in hydrogen changed from 1H to 2H. A sufficiently long purging time changed the main hydrogen isotope incorporated in the film back to 1H. A multiple short pulse scheme was used to study th…

ToF-ERDAMaterials scienceHydrogenAnalytical chemistrychemistry.chemical_elementZincAtomic layer depositionchemistry.chemical_compoundImpuritysinkkioksidiMaterials ChemistryThin filmDeposition (law)Heavy waterdiethylzincSurfaces and InterfacesatomikerroskasvatusEngineering (General). Civil engineering (General)heavy waterSurfaces Coatings and FilmschemistryDeuteriumALDvetyZnOTA1-2040ohutkalvot
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Donor and acceptor guided modes in photonic crystal fibers.

2000

We present a triangular photonic-crystal-fiber structure that exhibits guided modes simultaneously above and below the first conduction band. We achieve this configuration by decreasing the size of one of the airholes (the defect) in a specific triangular lattice. More generally, we analyze the behavior of guided modes that depends on the size of the defect. Defects generated by decreasing or increasing the size of one of the holes produce donor or acceptor guided modes, respectively, in analogy with impurity levels in solid-state crystals. We conclude that the guiding mechanism for both donor and acceptor modes is produced by a unique phenomenon of multiple interference by a periodic struc…

Total internal reflectionOpticsMaterials sciencebusiness.industryGuided-mode resonanceImpurityHexagonal latticebusinessAcceptorRefractive indexAtomic and Molecular Physics and OpticsPhotonic crystalPhotonic-crystal fiberOptics letters
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Trace element behavior in the fluidized bed gasification of solid recovered fuels

2013

Gasification of biomass and recycled fuels is of particular interest for the efficient production of power and heat. Trace elements present as impurities in the product gas should be removed very efficiently. The objective of this work has been to develop and test thermodynamic models for the reactions of trace elements with chlorine and sulfur in the gasification processes of recycled fuels. In particular, the chemical reactions of trace elements with main thermochemical conversion products, main ash components, and bed and sorbent material are implemented into the model. The possibilities of gas cleaning devices in condensing and removing the trace element compounds are studied by establi…

Trace elementsMunicipal solid wasteWaste managementChemistryThermodynamic equilibriumGeneral Chemical EngineeringOrganic ChemistryTrace elementEnergy Engineering and Power TechnologyBiomassgasificationmodeling/dk/atira/pure/sustainabledevelopmentgoals/responsible_consumption_and_productionthermodynamic equilibriumFuel TechnologyImpurityFluidized bedEnvironmental chemistrysolid wasteSDG 12 - Responsible Consumption and ProductionProduct gasta215Fuel
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UV light induced processes in pure and doped AlN ceramics

2021

The present research has been sponsored by the Latvian Council of Science , Grant No. lzp-2018/1-0361 “Research of luminescence mechanisms and dosimeter properties in prospective nitrides and oxides using TL and OSL methods “; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 73950 , project CAMART 2

UV light irradiationPhotoluminescenceMaterials scienceRecombination luminescenceThermoluminescenceAnalytical chemistry02 engineering and technology01 natural sciences7. Clean energyThermoluminescenceInorganic ChemistryImpurity0103 physical sciencesEmission spectrumElectrical and Electronic EngineeringPhysical and Theoretical ChemistryPhotoluminescenceSpectroscopy010302 applied physicsDopantPhotoelectric effectOrganic ChemistryDopingPhotoelectric effect021001 nanoscience & nanotechnologyAtomic and Molecular Physics and OpticsElectronic Optical and Magnetic Materials:NATURAL SCIENCES [Research Subject Categories]0210 nano-technologyLuminescenceAluminium nitrideOptical Materials
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Comparative Mössbauer spectroscopic study of iron impurities in ZnSe

2001

Abstract An anomalous spectral doublet attributed to Fe 2+ impurity pairs is observed in Mossbauer absorption spectra of 57 Fe 0.01 Zn 0.99 Se below room temperature. In Mossbauer emission experiments, ZnSe: 57 Co polycrystal and powder sources exhibit below 45 K the nucleogenic Fe 1+ valence state born as an after effect of the electron-capture decay of 57 Co. Above 8 K, the proportion of the nucleogenic Fe 1+ decreases under the effect of the thermally activated Fe 1+ →Fe 2+ relaxation. The activation energy is estimated to 0.004 eV. While nucleogenic Fe 1+ is absent in ZnSe: 57 Co single crystal spectra, increasing proportions are detected in samples with an enhanced specific surface. Th…

Valence (chemistry)Mössbauer effectAbsorption spectroscopyChemistryInorganic chemistryAnalytical chemistryGeneral ChemistryActivation energyCondensed Matter PhysicsNucleogenicImpurityMössbauer spectroscopyGeneral Materials ScienceSingle crystalJournal of Physics and Chemistry of Solids
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Analytical chemistry on many-center chiral compounds based on vibrational circular dichroism: Absolute configuration assignments and determination of…

2019

The absolute configuration of a chiral molecule is key to its biological activity. Being able to find out what this configuration is, is thus crucial for a wide range of applications. The difficulties associated with such a determination steeply rise as the number of chiral centers in a given compound becomes larger. Concurrently, it becomes increasingly more challenging to determine the levels and identity of potential stereochemical contaminants in a given sample with one and the same technique, leading in practice to extensive and laborious efforts employing multiple analytical techniques. Here, experimental and theoretical studies based on Vibrational Circular Dichroism (VCD) are presen…

Vibrational optical activity02 engineering and technologyCenter (group theory)01 natural sciencesBiochemistrySpectral lineAnalytical ChemistrySynthetic drugsSDG 3 - Good Health and Well-beingComputational chemistryStereochemistryEnvironmental ChemistryAbsolute configurationSpectroscopyFELIX Condensed Matter PhysicsChemistryDiastereomeric impurity levelsPharmaceutics010401 analytical chemistryAbsolute configurationDiastereomer021001 nanoscience & nanotechnology0104 chemical sciencesDensity functional calculationVibrational circular dichroism/dk/atira/pure/sustainabledevelopmentgoals/good_health_and_well_being0210 nano-technologyDensity functional calculation
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Genetic Algorithm Modeling for Photocatalytic Elimination of Impurity in Wastewater

2019

The existence of C.I. Acid Yellow 23 (AY23) in water causes a great danger to people and society. Here, we suggest an advanced technique which predicts the photochemical deletion of AY23. The genetic algorithm (GA) technique is suggested in order to predict the photocatalytic removal of AY23 by implementing the Ag-TiO\(_{2}\) nanoparticles provided under appropriate conditions.

WastewaterImpurityComputer scienceGenetic algorithm0202 electrical engineering electronic engineering information engineeringPhotocatalysisOrder (ring theory)020201 artificial intelligence & image processing02 engineering and technology021001 nanoscience & nanotechnology0210 nano-technologyBiological system
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