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1.
Spectroscopic properties of Er3+ ions in sodium borate glass have been studied. The indirect and direct optical band gaps (Eopt) and energy level parameters (RacahE 1, E2 and E3), spin-orbit (ξ4f) and configurational interaction (α)) are evaluated. Spectral intensities for various absorption bands of Er3+ doped sodium borate glass are calculated. Using Judd-Ofelt intensity parametersΩ 2, Ω4, Ω6, radiative transition probabilities (A), branching ratios (β) and integrated absorption cross sections (Σ) are reported for certain transitions. The radiative lifetimes (τR) for different excited states are estimated. From the fluorescence spectra, the emission cross section (σP) for the transition,4I13/2 4I15/2 is reported.  相似文献   

2.
Luis A. Sarabia 《TEST》1982,33(1):64-85
Let (Ω, θ,J) be a finitely additive probabilistic space formed by any set Ω, an algebra of subsets θ and a finitely additive probabilityJ. In these conditions ifF belongs toV 1 (Ω, θ,J) there existsf, element of the completion ofL 1 (Ω, θ,J), such thatF(E)=∫ E fdJ for allE of θ and conversely. This integral representation gives sense to the following result, which is the objetive of this paper, in terms of the, point function: If β is a subalgebra of θ, for everyF ofV 1 (Ω, θ,J) there exists a unique element ofV 1 (Ω, β,J) which we note down byE(F/gb), conditional expetation ofF given β. E(F/β) is characterized by (E(F/β),G)=(F, G) for every ofV (Ω,β, J). Aside from this, the mappingE(./β):V 1 (Ω, θ,J)→V 1 (Ω, β,J) is linear, positive, contractive, idempotent andE(J/β)=J. IfF is ofV p (Ω, θ,J),p>1,E(F/β) is ofV p (Ω, β,J).
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3.
Ultrasonic velocities and densities of the drug Parvon-spas in binary mixtures of water with methanol (MeOH), ethanol (EtOH), and propan-1-ol (1-PrOH) have been measured over the complete solvent composition range at 10 mol% intervals at 25°C. Various acoustic parameters such as the acoustic impedance (Z), adiabatic compressibility (β), intermolecular free length (Lf), relative association (R.A.), molar volume (Vm), and molar sound velocity (Rm) have been calculated. In addition, excess functions, i.e., excess adiabatic compressibility (βE), excess intermolecular free length (LfE), excess molar volume (VE), excess ultrasonic velocity (UE), and excess acoustic impedance (ZE) for these three solvent mixtures in the absence and presence of the drug have been calculated. A different behavior of these parameters in these alcohol systems has been discussed in terms of the length of the alcohol molecule, the molecular volume, as well as inter/intramolecular interactions of these molecules.  相似文献   

4.
Electrolytic conductivities of potassium halides, KX (X = Cl, Br, I) have been investigated in 10, 20, and 30 mass% glycerol + H2O mixtures at 298.0, 308.0, and 318.0 K. The conductance data have been analyzed by the Fuoss-conductance–concentration equation in terms of the limiting molar conductance (Λ0), the association constant (K A ), and the distance of closest approach of ion (R). The association constant (K A ) tends to increase in the order: 10 mass% < 20 mass% < 30 mass% glycerol + water mixtures, while it decreases with temperature. Thermodynamic parameters ΔH 0, ΔG 0, and ΔS 0 are obtained and discussed. Also, Walden products (Λ0η) are reported. The results have been interpreted in terms of ion–solvent interactions and structural changes in the mixed solvents.  相似文献   

5.
Using the optical absorption spectra and the Judd-Ofelt theory, intensity parameters (Ωλ) are calculated. Radiative lifetimes (T R), branching ratios (β) and integrated absorption cross sections (Σ) are reported for certain excited levels of Nd3+ ion in lead acetate glass.  相似文献   

6.
In this study, uniaxial compressive strength (UCS) tests were carried out to investigate the anisotropic strength behavior of laminated sandstones selected from submarine fan deposits in the Neogene Adana Basin of Southern Turkey. The core specimens were prepared at orientation angles (β) of 0°, 30°, 45°, 60°, and 90° with respect to the planes of lamination. U-type strength anisotropy with strength anisotropy ratios (Rc = σ90min) varying between 1.29 and 1.74 were found, referring to a low degree of anisotropy. An attempt has been made to estimate the anisotropic UCS behavior taking into account orientation angles, unit weight (γ) and porosity (n) as independent variables by multivariate regression analysis. The second orders of each independent variable as well as the third order of the orientation angle values were also considered in regression analyses to take into consideration their nonlinear relationships on UCS. The prediction performance of the best fit regression model was evaluated by the standard error of estimate (SEE), the coefficient of multiple determination (R 2), and the adjusted coefficient of multiple determination (Ra2 R_{a}^{2} ), which were obtained as 2.27, 0.927, and 0.923, respectively, indicating high prediction capacity.  相似文献   

7.
Densities and viscosities were measured for binary mixtures of isoamyl alcohol with 2-methoxyethanol, 2-ethoxyethanol, and 2-butoxyethanol over the entire range of composition at 303.15 K, 313.15 K, and 323.15K and ultrasonic speeds and refractive indices at 303.15 K under atmospheric pressure. From the experimental values of density, viscosity, ultrasonic speed, and refractive index, the values of excess molar volume (V E), viscosity deviations (Δη), deviations in isentropic compressibility (ΔK S ), and excess molar refraction (ΔR) have been calculated. The excess or deviation properties were found to be either negative or positive, depending on the molecular interactions and the nature of liquid mixtures.  相似文献   

8.
Results are presented for binary intermolecular interactions and thermophysical properties in the temperature range between 70K and 1,000K of gaseous fluorine (F2), and between 200K and 1,000K of chlorine (Cl2), bromine (Br2), and iodine (I2). Our studies are carried out with an (n − 6) Lennard-Jones temperature-dependent potential (LJTDP). The underlying model takes into account the influence of vibrational excitations on the equilibrium distance R m(T) and potential well depth e(T){\varepsilon(T)} . The potential parameters at T = 0K have been obtained by minimization of the sum of squared deviations between experimentally determined and calculated second pVT- and acoustic virial coefficients, B and β, and viscosities η, normalized to their relative experimental error a exp. The majority of the available experimental data are well reproduced within their experimental errors. Tables and fitting formulae for a fast and reliable prediction of the thermophysical properties and potential parameters are also presented.  相似文献   

9.
The electrical conductivity (σ), Hall coefficient (R H, and thermopower (α) of Sm x Pb1 − x Te have been measured at temperatures from 80 to 800 K. The results demonstrate that the Sm x Pb1 − x Te solid solutions with x ≤ 0.04 are p-type semiconductors. We have determined the electron effective mass at the conduction band bottom (m n = (0.031 ± 0.001)m 0) and Fermi level (m* = (0.06 ± 0.001)m 0) and the hole effective mass (m p = (0.34 ± 0.001)m 0). The temperature-dependent σ, R H, and α data are interpreted in terms of a model with two carrier types.  相似文献   

10.
The SiKβ fluorescence X-ray and infra-red absorption spectra of Na2O-TiO2-SiO2 and K2O-TiO2-SiO2 glasses have been measured in order to study the Si-O bonding as a function of the composition of glass. The chemical shifts of the SiKβ peak relative to that of silica glass [Δλ=λ(SiO2)-λ(specimen)>0] and the wavenumbers of the infra-red absorption peaks around 950cm−1 and 1100 cm−1 have been determined from the spectra. The SiKβ chemical shift in both series of glasses increased with increasing total content of R2O and TiO2 and with decreasing ratio of TiO2/(K2O+TiO2), where R2O represents Na2O or K2O. The infra-red peaks around 950 cm−1 and 1100 cm−1 shifted towards lower wavenumbers with increasing total content of R2O and TiO2 and with decreasing ratio of TiO2/(R2O+TiO2). These experimental facts were interpreted as showing that the Si-O bond in glass was weakened as the total content of R2O and TiO2 increased and that the Si-O bond was weakened by R2O more than by TiO2.  相似文献   

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