Polarizability
Mostrando 25-36 de 58 artigos, teses e dissertações.
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25. Mathematical modeling of electro-rotation spectra of small particles in liquid solutions: Application to human erythrocyte aggregates
Electro-rotation can be used to determine the dielectric properties of cells, as well as to observe dynamic changes in both dielectric and morphological properties. Suspended biological cells and particles respond to alternating-field polarization by moving, deforming or rotating. While in linearly polarized alternating fields the particles are oriented alon
Brazilian Journal of Medical and Biological Research. Publicado em: 2004-02
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26. Cálculo ab initio de intensidades Raman dinâmicas utilizando a teoria da resposta linear
In this paper a methodology for the computation of Raman scattering cross-sections and depolarization ratios within the Placzek Polarizability Theory is described. The polarizability gradients are derived from the values of the dynamic polarizabilities computed at the excitation frequencies using ab initio Linear Response Theory. A sample application of the
Química Nova. Publicado em: 2003-08
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27. Symmetry energy coefficients for asymmetric nuclear matter
Symmetry energy coefficients of asymmetric nuclear matter generalized are investigated as the inverse of nuclear matter polarizabilities with two different approaches. Firstly a general calculation shows they may depend on the neutron-proton asymmetry itself. The choice of particular prescriptions for the density fluctuations lead to certain isospin (n-p asy
Brazilian Journal of Physics. Publicado em: 2003-06
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28. Testes de desempenho de eletrodos: eletrodos de referência
This paper is designed to divulge some tests found in books, articles and international technical standards, by means of which it is possible to evaluate the performance of reference electrode widely used in potentiometric and voltammetric methods. The reference potential (Eref), junction resistance (Rj), the ability of keeping up the potential when current
Química Nova. Publicado em: 2000-08
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29. Espalhamento Raman em heteroestruturas semicondutoras de Si/Ge
We have used Raman spectroscopy to study the lattice dynamics of Ge/Si semiconductor heterostructures, both experimentally and theoretically. The study was performed in a broad spectral range (from 2 cm-1 up to 600 cm-1), which includes the acoustical folded phonons, interfaces phonons, and confined optical phonons. We have used several experimental systems:
Publicado em: 1995
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30. Estudo teorico das relações entre estrutura quimica e atividade biologica de antagonistas do calcio da classe 1,4-diidropiridinas
We have made a theoretical study whose purpose is to correlate the geometrical and physico-chemical properties of a series of 45 compounds to their biological activities. The compounds used in this study were the 2,6-dimethyl-3,5-carbomethoxy-4-(substituted)-phenyl-1,4-dihydropyridine (DHP) derivatives, where a large variety of functional groups were substit
Publicado em: 1992
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31. Phase conjugation and transverse self-phase modulation in Cr+3 doped crystals / Conjugação de fase e modulação transversal de fase em cristais dopados com Cr+3
In this work we studied theoretical and experimentally the effects of Phase Conjugation by Degenerate Four Wave Mixing and Transversal Phase (PCD4WM) Modulation in Cr+3 doped crystals. We studied the PDC4WM in Al2O3:Cr+3 (ruby) and GdAlO3:Cr+3 with on Ar laser (at λ= 514 nm) and obtained a good agreement between our experimental and theoretical results
Publicado em: 1989
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32. Dielectric constant of atomic fluids with variable polarizability
The Clausius-Mossotti function for the dielectric constant is expanded in terms of single atom and pair polarizabilities, leading to contributions that depend on both the trace and the anisotropy of the pair-polarizability tensor. The short-range contribution of the anisotropic part to the pair polarizabilities has previously been obtained empirically from l
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33. Relation between the local field at large distances from a charge or dipole and the dielectric constant
The local field at large distances from a charged or dipolar impurity in a nonpolar polarizable fluid is related to the dielectric constant of the medium. The predicted local field agrees accurately with molecular dynamics results. In contrast, the usual continuum theory prediction is only accurate to first order in the polarizability and leads to serious er
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34. High Pressure Studies of Solvent Effects on Anthracene Spectra
Measurements have been made of the effect of pressure on the peak location and peak shape for anthracene in a variety of liquid and plastic environments; both absorption and fluorescence studies were made. The results are discussed from two standpoints: in terms of the dielectric model and of a configuration coordinate model. For the latter model, the change
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35. Calculation of translational friction and intrinsic viscosity. I. General formulation for arbitrarily shaped particles.
A general method for calculating translational friction and intrinsic viscosity is developed through exploiting relations between hydrodynamics and electrostatics. An approximate relation xi = 6 pi eta 0C between the translational friction coefficient xi of a particle (eta 0: solvent viscosity) and its capacitance C was derived previously. This involved orie
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36. Polarizable molecules in the vibrational spectroscopy of water
We examine the role of electronic polarizability in water on short (tens of femtoseconds), intermediate (hundreds of femtoseconds), and long (≈1 ps) time scales by comparing molecular dynamics results to experimental data for vibrational spectroscopy of HOD in liquid D2O. Because the OH absorption frequency is sensitive to the details of the atomic forces
National Academy of Sciences.