Atomic Excitation
Mostrando 1-12 de 30 artigos, teses e dissertações.
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1. Sinais de fundo em análise instrumental: uma discussão essencial em cursos de graduação
Understanding instrumental analysis is essential for obtaining reliable analytical results required by chemists in a variety of research areas and industrial activities. All instrumental techniques involve undesirable background (BG) signals originated either from concomitants in the sample or by spurious (e.g. electrical or optical) effects intrinsically re
Quím. Nova. Publicado em: 2017-02
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2. Nonperturbative treatment of the screened-Coulomb contribution of projectile-electron loss
The electron-loss cross section of He+ ions impinging upon noble-gas targets (2≤Z2≤36) is calculated by using the coupled-channel method for the active projectile electron in the static screened field of the target atom. The calculations show a saturation of the projectile-electron-loss cross section with increasing target atomic number. This saturation
Publicado em: 2011
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3. Study of the photoluminescent properties of MgTiO3 powder and thin films obtained by the polimeric precursor method / Estudo das propriedades fotoluminescentes de pós e filmes finos de MgTiO3 obtidos pelo método dos precursores poliméricos
In this study, MgTiO3 (MTO) powders and thin films that crystallize in a perovskite ilmenite crystalline structure were obtained and characterized. MTO were synthesized by the polymeric precursor method (PPM), which allows obtaining structurally ordered and disordered structures. In addiction, the photoluminescent properties were investigated as a function o
Publicado em: 2011
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4. Optical and electrical diagnostics of microdischarges at moderate to high pressure in argon
Microdischarges at moderate to high pressure in argon were investigated. A hole opening diameter of 500 µm direct current (dc) microhollow cathode discharges (MHCD) were characterized by electrical measurements and optical emission spectroscopy (OES) for pressures ranging between 90 and 800 Torr and current from 5 to 20 mA. Current-voltage characteristic cu
Brazilian Journal of Physics. Publicado em: 2010-12
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5. UV dominant optical emission newly detected from radioisotopes and XRF sources
The current paper reports first and definite experimental evidence for γ-, X-, or β radiation causing UV dominant optical radiation from (1) radiochemicals such as 131I; (2) XRF sources such as Rb XRF source present as salts; and (3) metal sources such as 57Co, and Cu XRF sources. Due to low quantum yield a need arose to develop two techniques with narrow
Brazilian Journal of Physics. Publicado em: 2010-03
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6. 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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7. Análise de cerâmicas arqueológicas do Sambaqui do Bacanga (São Luís, MA) por EDXRF portátil
Sambaqui do Bacanga archaeological site is located in the Island of São Luis -Maranhão Brazil, in the region bathed by the Bacanga River. A tratigraphic collection of 78 ceramic fragments was collected during the years 2005 and 2006, to perform a qualitative analysis of the chemical elements employing a Portable System of Energy Dispersive X-ray Flu
Publicado em: 2009
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8. Estado fundamental e excitações coletivas de condensados de Bose-Einstein espinoriais / Ground state and collective excitations od spinor Bose-Einstein condensates
In the framework of the Bogoliubov theory, we determined the equilibrium configurations and the collective excitations of a homogeneous Bose-Einstein S = 1 spinor condensate, in the presence and absence of an externa1 magnetic field. In this thesis we found the equilibrium configurations as function of the parameters and m, where q is the intensity of the qu
Publicado em: 2007
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9. Processos binários em átomos de Rydberg / Binary process in Rydberg atoms
This dissertation seeks to address some of the characteristics of collisional processes in ultracold Rydberg atoms. With a Maqneto-Optical Trap (MOT), we trapped a sample of 85Rb, an alkaline metal element, in a region of about lmm at a temperature of a few hundreds of ?K, known in the literature as the "ultracold" regime. The 85Rb atoms are then excited to
Publicado em: 2006
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10. Theoretical study of transition metal monocarbides: MnC and CoC. / Estudo teórico de monocarbetos de metais de transição: MnC e CoC
In this work, high level ab initio multiconfigurational methods were employed to study the electronic structures and chemical bondings of several electronic states of two 3d transition metal monocarbides: MnC and CoC. The lowest-lying quartet, sextet, and octuplet electronic states of MnC, correlating with the three lowest-lying atomic dissociation channels,
Publicado em: 2006
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11. Armazenamento e distribuição de pulsos ópticos com conversão em múltiplos comprimentos de onda
Based in the effect of the Electromagnetically Induced Transparency (EIT) and the storage of light in atomic medium, we propose multi-wavelength optical pulse conversion. Starting from coupled Maxwell-Bloch equations, we simulate the propagation of the optical pulses resonant with electric dipole transition in the atomic system. Considering a three level
Publicado em: 2005
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12. Glow discharge plasma properties of gases of environmental interest
Experiments in a low pressure glow discharge on gases of environmental relevance: CO2,CO y O2 are reported. We studied the various atomic processes: ionization, excitation and molecular dissociation with typical discharge parameters of p~0.6 mbar, I< 0.1 A and V~1100 Volts. We used visible and near UV spectroscopy to observe the emitted radiation on both ele
Brazilian Journal of Physics. Publicado em: 2004-12