Radiative Properties
Mostrando 1-12 de 33 artigos, teses e dissertações.
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1. JUDD-OFELT ANALYSIS OF Tb3+ AND UPCONVERSION STUDY IN Yb3+-Tb3+ CO-DOPED CALIBO GLASSES
We report on the study of the spectroscopic properties in Ytterbium-Terbium (Yb3+-Tb3+) co-doped calcium lithium borate (CaLiBO) glasses, with the study’s focus being on the upconversion process. Intensity parameters Ωλ for CaLiBO:Tb3+ are determined by the Judd-Ofelt method to be Ω2 = 15.5 × 10-20 cm2, Ω4 = 1.90 × 10-20 cm2 and Ω6 = 3.69 × 10-20 c
Quím. Nova. Publicado em: 2020-02
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2. Temperature and Deposition Time Effect on Properties and Kinetics of CdSe and CdS0.25Se0.75 Films Deposited by CBD
CdSe and CdS0.25Se0.75 thin films were grown by the Chemical Bath Deposition technique at different temperatures (50-90°C) and deposition times (5-180 min). Both kinds of films are polycrystalline, constituted by nanostructured clusters of particles. CdSe films consist in a mixture of cubic and hexagonal phases (4-8 nm crystal size), whereas only the hexago
Mat. Res.. Publicado em: 26/06/2017
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3. Shear Properties of Carbon Fiber/Phenolic Resin Composites Heat Treated at High Temperatures
ABSTRACT Carbon fiber/phenolic resin composites have long been used as ablative materials in rocketry. Ablation is a complex multiscale problem where radiative and convective heating leads to the pyrolysis of phenolic resin matrix, resulting in the formation of a porous insulation char as thermal protection. This study investigates the shear properties evolu
J. Aerosp. Technol. Manag.. Publicado em: 2016-09
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4. Low Temperature Synthesis of Luminescent RE2O3:Eu3+ Nanomaterials Using Trimellitic Acid Precursors
[RE(TLA)·(H2O)n:Eu3+] (RE3+: Y, Gd and Lu; TLA: trimellitic acid) precursor complexes were synthesized by an one step aqueous co-precipitation method. After annealing for 1 h, RE2O3:Eu3+ nanophosphors were formed through the benzenetricarboxylate low temperature thermolysis method (500-1000 ºC). The compounds were characterized by using different technique
J. Braz. Chem. Soc.. Publicado em: 2015-12
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5. Simulação da dinâmica do estado excitado em semicondutores orgânicos / Simulation of the excited state dynamics in organic semiconductors
In the present work, the Monte Carlo method and the direct numerical integration of the Master Equation were employed to simulate the excitation spectral diffusion process in light emitting polymeric systems. The methodology employed a competition among the internal intra-molecular relaxation, the inter-molecular incoherent energy transfer via Förster mecha
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 25/04/2012
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6. Spectroscopic study of molecular dynamics and packing in organic semiconductors / Estudo espectroscópico da dinâmica molecular e empacotamento em semicondutores orgânicos
In this dissertation we present a study of the molecular dynamics and packing in organics semiconductor with different conjugated chains lengths using a of multi-techniques approach, in particular, Nuclear Magnetic Resonance (NMR), Wide Angle X-ray Scattering (WAXS), Differential Scanning Calorimetry (DSC), Raman spectroscopy, UV-Vis absorption and fluoresce
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 22/07/2011
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7. Propriedades Ãpticas dos vidros Er3+:PbPO4 / Optical Properties of the Er3+:PbPO4 Glasses
In this work we employ several techniques to investigate the optical properties of moderately high Er3+-doped lead phosphate (EDLP) glasses. The third-order optical susceptibility, χ3, and dispersion of the linear refractive index, n0(λ), of Er3+:PbPO4 were measured in the wavelength range between 400 and 1940 nm by using the spectrally resolved fe
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 02/07/2010
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8. A comparative study of the application of differential evolution and simulated annealing in radiative transfer problems
The radiative transfer phenomenon is modeled by an integro-differential equation known as Boltzmann equation. This equation describes mathematically the interaction of the radiation with the participating medium, i.e., a medium that may absorb, scatter and emit radiation. In this sense, this work presents a study regarding the estimation of radiative propert
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2010-12
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9. Application of neuro-fuzzy systems for the solution of radiative transfer inverse problems / Aplicação de redes neuro-fuzzy para a solução de problemas inversos em transferência radiativa
In this thesis is proposed an implementation for solving the inverse problem with the estimates of radiative properties (the single scattering albedo, the optical thickness of the media and the diffuse reflectivities) by the values of the intensities of radiation that leaves the participant medium using a hybrid approach of neuro-fuzzy systems, which combine
Publicado em: 2010
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10. An explicit formulation for the inverse transport problem using only external detectors: Part I: computational modelling
In the present work the inverse problem of identification of radiative properties, the total extinction and scattering coefficients, is analyzed and explicitly formulated based in an elementary semi-group theory. The Chandrasekhar discrete ordinates finite dimensional approximation of the angular variables is used for the direct problem representation with t
Computational & Applied Mathematics. Publicado em: 2010
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11. Estudos espectroscópicos e estruturais dos polímeros de coordenação 2D, ∞[Tb(DPA)(HDPA)] e ∞[Gd(DPA)(HDPA)]
This paper presents the synthesis of the coordination polymers ∞[Ln(DPA)(HDPA)] (DPA=2,6-pyridinedicarboxylate; Ln= Tb and Gd), their structural and spectroscopic properties. The structural study reveals that the ∞[Ln(DPA)(HDPA)] has a single Ln+3 ion coordinated with two H2DPA ligands in tridentade coordination mode, while two others H2DPA establish a s
Química Nova. Publicado em: 2009
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12. Construção de uma armadilha magneto-ótica para aplicações em informação quântica e física atômica / Construction of a Magnet-Optical Trap for Aplications at Quantum Information and Atomic Physics
We built a magneto-optical trap (MOT) for rubidium as a first step for the trapping of a cloud of cold atoms in a periodic potential formed by light beams. This system will be used for experiments in atom physics, with possible applications in quantum information. A MOT is necessary to avoid the problems imposed by the thermal agitation of the atoms to the m
Publicado em: 2009