Synchrotron Radiation
Mostrando 25-36 de 109 artigos, teses e dissertações.
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25. Photon stimulated ion desorption of condensed CO2 at ~ 85 K studied by synchrotron radiation
Photon stimulated ion desorption (PSID) from condensed carbon dioxide has been studied for photon excitation energies ranging from 93 to 193 eV. PSID studies have been performed at the Brazilian synchrotron light source (LNLS), Campinas, during a multi-bunch operation mode of the storage ring. The results showed that after photon excitation several ions deso
Brazilian Journal of Physics. Publicado em: 2006-09
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26. Ionic desorption in valence- and core- excited polymers: poly(vinyl chloride) and poly(vinylidene chloride)
Photon stimulated ion desorption (PSID) studies have been performed in poly(vinyl chloride) (PVC) and poly(vinylidene chloride) (PVDC) using synchrotron radiation, covering from valence to core electron (Cl 2p and C 1s) energy ranges. Data acquisition was performed at the TGM beam line from the Brazilian Synchrotron Light Source (LNLS), operating in a multi-
Brazilian Journal of Physics. Publicado em: 2006-06
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27. Espectroscopia de fotoelétrons de limiares de átomos e moléculas
A threshold photoelectron spectrometer applied to the study of atomic and molecular threshold photoionization processes is described. The spectrometer has been used in conjunction with a toroidal grating monochromator at the National Synchrotron Radiation Laboratory (LNLS), Brazil. It can be tuned to accept threshold electrons (< 20 meV) and work with a powe
Química Nova. Publicado em: 2006-02
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28. Avaliação do desenvolvimento de girassol por meio de analise de proteinas e metaloproteinas / Evaluation of sunflower development based on protein metalloprotein analysis
This work describes an evaluation of sunflower (Helianthus annuus L.) growth when it is submitted to seven treatments, and their interrelation with proteins and metalloproteins analyses. Metal ion solutions (Cd, Cu, Pb and Zn) were added to the substrate in four treatments. In another two, used as controls, the plants were irrigated only with deionized water
Publicado em: 2006
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29. Photoabsorption and photoionization studies of the amino acid proline in the VUV region
Ionic fragmentation of the sublimated amino acid DL-proline has been studied using time-of-flight mass spectrometry and synchrotron radiation. Total ion yield and mass spectra were recorded in the 13 to 21.6 eV energy range. Partial ion yields have been calculated for the produced fragments and the results analyzed in a comparative way. Mass spectrum of prol
Brazilian Journal of Physics. Publicado em: 2005-12
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30. Relativistic jets and accretion phenomena associated with galactic and extragalactic black holes
More than a dozen binary star systems hosting stellar-mass black holes have been discovered in our galaxy. Some of them eject collimated relativistic jets with apparent velocities larger than the light speed. These objects have been named microquasars thanks to their similarity with the distant quasars or active nuclei of galaxies that host supermassive blac
Brazilian Journal of Physics. Publicado em: 2005-12
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31. Analysis of gyro-synchrotron radiation from solar bursts in complex magnetic environment / Estudo da radiação girossincrotrônica de explosões solares em ambientes de campos magnéticos complexos
Este trabalho descreve os resultados da aplicação do arcabouço de modelagem dinâmica CLUE para explorar como fatores alternativos, políticas públicas e condições de mercado influenciam o processo de ocupação da Amazônia. Trabalhos anteriores na Amazônia enfatizaram aspectos como distância a estradas, quase sempre desconsiderando a enorme heterog
Publicado em: 2005
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32. The potentialities of coherent X-radiation for self-assembled systems and liquid crystal research
The potentialities of coherent X-radiation for investigation of structural features of self-assembled systems and liquid crystals was studied using Monte Carlo techniques. The radiation spectra were simulated for the case of interaction of 20 MeV electrons with a liquid crystal, and the influence of the various crystal parameters was studied. The simulations
Brazilian Journal of Physics. Publicado em: 2004-09
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33. SR-TXRF detection limit reduction using thin polymer film substrates
Three different substrates for the analysis of liquid samples by Total Reflection X-Ray Fluorescence with Synchrotron Radiation (SR-TXRF) were investigated and compared: Lucite (Perspex), Kimfoil and Mylar. Dry targets were prepared by pipetting 5 mul aliquotes of the liquid samples (synthetic standards and fresh water samples) on the different substrates. A
Brazilian Journal of Physics. Publicado em: 2004-09
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34. X-ray scattering from self-assembled InAs islands
In this work several structural and chemical properties of self-assembled InAs islands grown on GaAs(001) are studied using surface x-ray scattering with synchrotron radiation. The technique of x-ray diffraction under grazing incidence condition was employed to differentiate coherent and incoherent islands. We used a model of a strained pyramidal island to i
Brazilian Journal of Physics. Publicado em: 2004-06
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35. Estudos de ionização de moléculas poliatômicas de interesse tecnológico.
Complex polyatomic compounds are increasingly being used for modern technological applications, e.g., those related to the semiconductor industry, generation of new materials etc. However, there is a big lack of knowledge of the fundamental properties of such relevant chemical species, and more investigations of them are highly desirable. In the above contex
Publicado em: 2004
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36. Estudo de propriedades estruturais e magneticas de filmes epitaxiais de MnAs sobre GaAs (001) / Study of the structural and magnetic properties of epitaxial MnAs films on GaAs(001)
Neste trabalho foram estudados filmes finos de MoAs crescidos por epitaxia de feixe molecular em substratos de GaAs (001). As propriedades magnéticas destas hetero-estruturas (filme magnético sobre um substrato semicondutor) são fortemente dependentes das propriedades estruturais do filme de MoAs que foram estudadas detalhadamente utilizando técnicas de
Publicado em: 2004