Radiative Energy Transfer
Mostrando 1-12 de 17 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. Espectroscopia ultrarrápida do polímero semicondutor luminescente MEH-PPV com excitação no ultravioleta / Ultrafast spectroscopy of the luminescent semiconducting polymer MEH-PPV with ultraviolet excitation
The optoelectronics industry is currently undergoing a transition period in which inorganic materials are being replaced by organic materials, oligomers and polymers, in the fabrication of some types of devices. However, factors such as low efficiency and low lifetime prevent polymer based devices on entering the market definitely. The solution of these issu
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 17/08/2012
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3. 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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4. Human thermal comfort: an irreversibility-based approach emulating empirical clothed-body correlations and the conceptual energy balance equation
Exergetic analysis can provide useful information as it enables the identification of irreversible phenomena bringing about entropy generation and, therefore, exergy losses (also referred to as irreversibilities). As far as human thermal comfort is concerned, irreversibilities can be evaluated based on parameters related to both the occupant and his surround
J. Braz. Soc. Mech. Sci. & Eng.. Publicado em: 2012-12
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5. Estudo da dependência da transferência espacial de energia com a concentração e com o tamanho de pontos quânticos de CdSe/ZnS
Os processos de transferência de energia em pontos quânticos (PQs) de CdSe/ZnS núcleo/casa (em inglês core/Shell) foram investigados nesse trabalho. As técnicas de absorção óptica, fotoluminescência e varredura da microluminescência foram aplicadas com o objetivo de entender os fenômenos de transferência de energia resolvida espacialmente para os
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 21/07/2011
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6. Estudo de parâmetros espectroscópicos de íons de Nd3+ no sistema vítreo SNAB (SiO2 Na2CO3 Al2O3 B2O3) nanoestruturado com nanocristais de CdS
In this work, experimental evidences have been observed for energy transfer from CdS nanocrystals, synthesized by the fusion method, to Nd3+ ions embedded in vitreous substrates (SNAB: SiO2 Na2O Al2O3 B2O3). These dot samples doped with neodymium have been investigated by combined optical absorption (OA), photoluminescence (PL), and time-resolved photolumine
Publicado em: 2010
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7. Silicon nanocrystals and zinc oxide nanowires with erbium / Nanocristais de silicio e nanofios de oxido de zinco com erbio
We present a study of erbium luminescence in silicon nanocrystals (nc-Si) and zinc oxide nanowires (nw-ZnO). Silicon nanocrystals are produced by annealing of amorphous sub-oxide thin films (SiOx) prepared by rf-sputtering varying the oxygen and erbium concentration during growth. Erbium is added by partially covering the silicon target surface with small pi
Publicado em: 2009
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8. Estudos espectroscópicos de vidros sódio aluminofosfatos co-dopados com Yb3+ e Tm3+ / Spectroscopic studies of glasses sodium aluminophosphatos co-dopad with Yb3+ and Tm3+
This work presents a throughout near-infrared and visible spectroscopic characterization of two sets of Yb3+ and Tm3+ codoped sodium aluminophosphate glasses, prepared in nitrogen and ambient atmospheres. In these samples, the Yb3+ ions are employed as efficient sensitizers of 0.98 µm excitation, with subsequent energy transfer to Tm3+ ions. Results are dis
Publicado em: 2007
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9. Transient convective heat transfer
In nature, as well as within the human-made thermal systems, the time-variable regimes are more commonly encountered, if not always, than the permanent regimes. Nevertheless, studies in convection are still more frequent in the permanent regimes, undoubtedly due to the related difficulties in calculation in terms of time and cost of computation. One may dist
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2005-03
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10. Modelagem da transferência de calor combinada por condução e radiação em isolantes térmicos de edificações
New insulation materials are being used in building industry to reduce electric energy consumption due to presence of HVAC (Heating, Ventilation and Air Conditioning) systems or to improve the thermal comfort of non-conditioned environments. An insulation material used in ceilings is the glass wool. The glass wool is considered as a semitransparent material,
Publicado em: 2005
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11. Fibras opticas de vidros teluritos de tungstenio para amplificação de grande largura de banda / Fibras opticas de vidros teluritos de tungstenio para amplificação de grande largura de banda
In optical communications, high capacity information transmission systems demand broadband optical amplifiers. Therefore, it has become increasingly necessary to manufacture devices with such characteristics. Optical amplifier devices based on Tellurite glasses are ideal for manufacturing broadband optical amplifiers. In the last few decades, most researcher
Publicado em: 2005
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12. Mixed convective and radiative heat transfer in an inclined rotating rectangular duct with a centered circular tube
A numerical study of steady state laminar forced and free convective and radiative heat transfer in an inclined rotating rectangular duct with a centered circular tube is reported for an hydrodynamically fully developed flow. The two heat transfer mechanisms of convection and radiation are treated independently and simultaneously. The coupled equations of mo
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2004-09