Electronic Excitation
Mostrando 13-24 de 81 artigos, teses e dissertações.
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13. Propriedades opticas de nanofios de InP / Optical properties of InP nanowires
Optical properties of InP nanowires grown by Vapor-Liquid-Solid (VLS) method in a Chemical Beam Epitaxy system were investigated by using micro-photoluminescence spectroscopy varying experimental parameters such as excitation power, emitted signal polarization and sample temperature. Due to polytypism (InP in cubic, zincblende (ZB), and hexagonal, wurtzite (
Publicado em: 2009
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14. Avaliação de desempenho de câmaras excitadas via linha de transmissão aplicáveis à compatibilidade eletromagnética. / Transmission line excited chamber performance evaluation applied to electromanetic compatibility.
This Thesis presents the proposition of a Transmission Line Excited Chamber configuration. This configuration is considered to be a potential solution for the constraints of reverberation chambers of nowadays. Among this constraints, e.g. the ones related to chamber operation at some MHz, is a physical restriction to implement in tests environments. Moreover
Publicado em: 2009
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15. Propriedades eletronicas e estruturais do xenonio implantado em silicio amorfo / Electronic and structural properties of xenon in amophous silocon
Esta tese mostra um estudo realizado sobre implantação de xenônio (Xe) em uma matriz amorfa de silício (a-Si) utilizando a técnica de Deposição Assistida com Feixe de Íons (IBAD). Para esta finalidade, um feixe de íons de Xe com energia de 1500 eV, obtido de um canhão tipo Kaufman, foi utilizado para a realização de sputtering de um alvo de silí
Publicado em: 2009
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16. Ordem-desordem: uma avaliação estrutural do Ba(ZrxTi1-x)O3 / Order-disorder: an evaluation structural of Ba(ZrxTi1x)O3
This work have as aim, the synthesis of ceramic powders of Ba(ZrxTi1x)O3 (x = 0, 0.25, 0.50, 0.75 and 1) by the polymeric precursor method and investigate the degree of structural order-disorder of these systems by different characterization techniques, such as: thermogravimetric analysis (TA), differential thermal analysis (DTA), X-ray diffraction (XRD), Ra
Publicado em: 2009
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17. Desenvolvimento de espectroscopia de plasma induzido por laser para aplicações em análise de patrimônio cultural: estudo de moedas de Um Cruzeiro de 1945 e Mil Réis de 1939 / DEVELOPMENT OF LASER INDUCED BREAKDOWN SPECTROSCOPY OF ONE "CRUZEIRO" FROM 1945 AND THOUSAND "RE¶IS" FROM 1939 FOR APPLICATIONS ON CULTURAL HERITAGE ANALYSIS: STUDY OF COINS
In this work, the technique of laser induced breakdown spectroscopy was developed for application in cultural heritage analysis in order to study coins of one \Cruzeiro" from 1945 and a thousand \R¶eis" from 1939, using a Nd:YAG laser operating in Q-switched mode. It had been determined the best conditions of laser and detection features such as pulse energ
Publicado em: 2008
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18. Uma avaliação experimental e numérica do efeito da rigidez geométrica na resposta dinâmica de estruturas esbeltas sujeitas à excitação de vento. / An experimental and numerical evaluation of the geometric stiffness effect on the dynamic response of slender structures under wind excitation.
Due to a politically and economically pragmatic decision, Brazil has chosen to intensely develop its cellular phone system, in order to bypass a stage of development. Once the decision has been taken, implementation was set in an explosive pace in the 1990s decade by installing tens of thousands of stations. As the electronic systems are usually more expensi
Publicado em: 2008
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19. Caracterização óptica de dispersões aquosas de nanotubos de carbono
It has been demonstrated that the electronic and optical properties of single-wall carbon nanotubes (SWNT) are strongly affected by the environment. This strong environmental effect is very relevant in analyzing the composition of carbon nanotube samples using optical techniques, especially in the case of separation experiments, where the SWNT environments a
Publicado em: 2008
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20. SYNTHESIS AND CHARACTERIZATION OF INORGANIC ION EXCHANGERS BASED ON MIXED OXIDE TIN-TITANIUM TO BE USED IN RECOVERY OF CADMIUM AND NICKEL AND PHOTOLUMINESCENT STUDIES / Síntese e caracterização de trocadores iônicos inorgânicos a base de óxidos mistos Estanho-Titânio para utilização na recuperação de Cádmio e Níquel e estudos fotoluminescentes
This work presents the synthesis, characterization and adsorption studies of inorganic ion exchangers based on mixed tin-titanium oxide for recovery of cadmium and nickel metals from aqueous effluents, discarded in the environment mainly through Ni-Cd battery. The exchangers were synthesized by sol-gel modified method using a mixture of tin(IV) chloride and
Publicado em: 2007
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21. Propriedades ópticas anômalas de poços e fios quânticos de InGaAs/InP vicinais
The dynamic and the lateral transport of carriers in quantum wells and quantum wires of InGaAs grown on vicinal InP substrates were investigated by spectrally and spatially resolved photoluminescence techniques. Simulation of the results of spectrally integrated photoluminescence using rate equations showed that the carrier capture and lifetime of the confin
Publicado em: 2007
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22. The effects of the plasmon-LO phonon interaction on the critical densities of RPA approach in a quasi-one-dimensional system
In this work we have studied the electron LO phonon interaction on the pair-correlation function g(x) and its dependence on the electronic density for a GaAs-AlGaAs rectangular quantum wire within the random-phase approximation (RPA). We assumed two different values of the wire width. As negative non-physical results are found for lower electronic densities
Brazilian Journal of Physics. Publicado em: 2006-06
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23. Coherent properties and rabi oscillations in two-level donor systems
Coherent properties and Rabi oscillations in two-level donor systems, under terahertz excitation, are theoretically investigated. Here we are concerned with donor states in bulk GaAs and GaAs - (Ga, Al)As quantum dots. We study confinement effects, in the presence of an applied magnetic field, on the electronic and on-center donor states in GaAs - (Ga, Al)As
Brazilian Journal of Physics. Publicado em: 2006-06
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24. SÃntese e caracterizaÃÃo de nanocristais luminescentes baseados em semicondutores II-VI para fins de aplicaÃÃo como biomarcadores
In this work we present synthetic procedures in aqueous medium for the obtention of luminescent II-VI (CdS/Cd(OH)2 and CdTe/CdS) semiconductor nanocrystals. These methodologies, based on colloidal chemistry, resulted in particles with a size average of 8,5 nm for the CdS/Cd(OH)2 system and 3,8 nm for the CdTe/CdS system. The optical properties of these mater
Publicado em: 2006