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The simple and easy methods of determining the important birefringent medium parameters have been presented. These methods allow us to measure some important quantities of the medium: the azimuth angle and the ellipticity angle of the first medium eigenvector, the phase difference introduced by the medium and intensity transmission coefficients of the two eigenwaves. The main idea of the methods described is based on the measurement of the four intensities of the linearly polarized light passed both: through the investigated medium, and through the medium and linear analyzer.  相似文献   
33.
X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) have been used to investigate the effect of reactive ion etching (RIE) on poly(methylhydrogensiloxane-co-dimethylsiloxane) surface in fluorine-based plasmas. Polysiloxane layers supported on the standard silicon wafers were etched using SF6 + O2 or CF4 + O2 plasmas. SEM studies show that the polysiloxane morphology depends on plasma chemical composition strongly. Presence of a columnar layer likely covered with a fluorine rich compound was found on the elastomer surface after the CF4 + O2 plasma exposure. After the SF6 + O2 or CF4 + O2 plasma treatment the polysiloxane surface enriches with fluorine or with fluorine and aluminum, respectively. Different morphologies and surface chemical compositions of the silicone elastomer etched in both plasmas indicate different etching mechanisms.  相似文献   
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We present a theoretical study of the motion of antihydrogen atoms in the Earth??s gravitational field near a material surface. We predict the existence of long-living quasistationary states of antihydrogen in a superposition of the gravitational and Casimir-van der Waals potentials of the surface. We suggest an interferometric method of measuring the energy difference between such gravitational states, hence the gravitational mass of antihydrogen.  相似文献   
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The formation of intramolecular hydrogen bonding by certain N‐substituted 2‐acylpyrroles has been demonstrated by B3LYP/aug‐cc‐pVDZ calculations, the quantum theory of atoms in molecules, and the natural bond orbital method. Total electron energy densities HBCP at the bond critical point of the H?O bond were applied to analyze the strength of these interactions. The relations between quantum theory of atoms in molecules, carbonyl stretching vibrational modes νC = O, and natural bond orbital parameters associated with the formation of the C–H?O interaction have been established. The short contacts were found experimentally in the crystal structure of a new 2‐acylpyrrole derivative 5‐chloro‐2‐oxopentyl‐1‐(5‐chloro‐2‐oxopentyl)pyrrolo‐2‐carboxylate. The influence of 2‐ and N‐substitution of 2‐acylpyrroles on C‐H?O interaction energy is discussed. It was found that the methylene group may act as a proton donor leading to a red‐shift or blue‐shift phenomenon of the νC–H stretching mode. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
38.
Optical spectra and luminescence decay curves were measured for thulium-doped YVO(4), GdVO(4), and LuVO(4) single crystals as a function of temperature in the 300-670 K temperature region. In spite of structural similarity, the three systems studied display significantly different transition intensities and nonradiative relaxation rates. It was found, in particular, that the peak value of the pump band absorption intensity diminishes by about 30% for Tm:YVO(4) and Tm:GdVO(4), and the effective emission cross section for the laser transition of Tm(3+) diminishes by a factor of 2 roughly when temperature increases from 300 to 500 K. An unusually small quantum efficiency of the upper laser level in Tm:LuVO(4) has been derived from the analysis of luminescence decay curves.  相似文献   
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Astounded at the regularity of convective structures observed in simulations of mesoscale flow past realistic topography, we investigate the computational aspects of a classical problem of flow over a heated plane. We find that the numerical solutions are sensitive to viscosity, either incorporated a priori or effectively realized in computational models. In particular, anisotropic viscosity can lead to regular convective structures that mimic naturally realizable Rayleigh–Bénard cells, which are unphysical for the specified external parameter range. Details of the viscosity appear to play a secondary role; that is, similar structures can occur for prescribed constant viscosities, explicit subgrid-scale turbulence models, ad-hoc numerical filters, or implicit dissipation of numerical schemes. This implies the need for a careful selection of numerical tools suitable for convection-resolving simulations of atmospheric circulations. The implicit large-eddy-simulation (ILES) approach using non-oscillatory schemes is especially attractive, as for under-resolved calculations it reproduces well the coarsened results of finely-resolved boundary layer convection.  相似文献   
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