测量液体粘滞系数实验的研究

本文利用液体的绝对速度理论得到液体的粘滞系数随温度变化的关系式，在不同的温度下测得液体的粘滞系数，找出液体的粘滞系数随温度变化的数学表达式。     

Electromigration effects in aluminum alloy metallization

An investigation of electromigration-induced failure in aluminum alloy films, with the major emphasis on aluminum-copper-silicon, was conducted. Flash evaporation was utilized for alloy deposition and yielded aluminum-copper films having electromigration resistance comparable to that of such films prepared by other techniques. Results for aluminum-copper-silicon and aluminum-copper were similar indicating the passive role of silicon in the presence of copper. Additions of four weight percent copper resulted in near-optimum electromigration resistance. In addition, hot-substrate deposition was beneficial in attaining greater lifetime. For films deposited on unheated substrates, or having lower copper contents, heat treatment seriously degraded electromigration resistance. Heat treatment effects were considered to be a consequence of copper redistribution. Lifetime decrease at large copper contents and possible saturation at large thicknesses were interpreted in terms of clustering of CuAl₂ precipitates. The superior reliability of copper-alloyed metallization when compared with aluminum or aluminum-silicon was clearly demonstrated. Lifetime improvement could be accounted for by the increased activation energy for the failure process in the aluminum-copper alloys.     

The excess volumes of tetrahydronaphthalene inn-alkanes at 10 and 25°C

The excess volume of mixing tetrahydronaphthalene with n-pentane, n-hexane, n-heptane, n-octane, n-dodecane and n-hexadecane have been measured over the whole composition range at two temperatures. The results are compared to the excess volume of mixing bicyclohexyl with the same solvents.     

X-ray determination of the mean amplitudes of vibration and debye temperatures of some rare earth monochalcogenides

The x-ray diffraction intensities of Bragg reflections have been measured at room temperature for thulium selenide, samarium sulphide, samarium selenide and samarium telluride. On the basis of a common amplitude approximation, the Debye-Waller factor, the mean amplitude of vibration and the Debye temperature have been evaluated. The values of the Debye temperatures and mean amplitudes of vibration are 176±16°K, 0·185 ± 0·017 Å (TmSe), 155 ± 7°K, 0·244 ± 0·012 Å (SmS), 153 ± 14°K, 0·221 ± 0·020 Å (SmSe) and 151 ± 20°K, 0·204 ± 0·027 Å (SmTe).     

Triangular lattice Potts models

In this paper we study the 3-state Potts model on the triangular lattice which has two- and three-site interactions. Using a Peierls argument we obtain a rigorous bound on the transition temperature, thereby disproving a conjecture on the location of its critical point. Low-temperature series are generated and analyzed for three particular choices of the coupling constants; a phase diagram is then drawn on the basis of these considerations. Our analysis indicates that the antiferromagnetic transition and the transition along the coexistence line are of first order, implying the existence of a multicritical point in the ferromagnetic region. Relation of the triangularq-state Potts model with other lattice-statistical problems is also discussed. In particular, an Ashkin-Teller model and the hard-hexagon lattice gas solved by Baxter emerge as special cases in appropriate limits.Supported in part by NSF grant No. DMR 78-18808.     

Stationary phases for gas chromatography; chemical stability of polysiloxanes

A number of polysiloxanes have been shown to be sensitive to acids when dissolved in chloroform. At 26O°C polysiloxanes were found to degrade under the influence of several compounds used or produced during the preparation of glass capillary columns.     

Rapid thermal annealing effects on the photoluminescence properties of molecular beam epitaxy-grown GaIn(N)As quantum wells with Ga(N)As spacers and barriers

This article describes the effects of rapid thermal annealing (RTA) on the photoluminescence (PL) emission from a series of GaIn(N)As quantum wells. Indium compositions of both 20% and 32% were examined with nominal N compositions of 1% or 2%. The N location was varied within our quantum structure, which can be divided into three regions: (1) quantum well, (2) Ga(N)As spacer layers at the barrier-to-well interface and well-to-barrier interface, and (3) barriers surrounding each quantum well. Eight combinations of samples were examined with varying In content, Ga(N)As spacer layer thickness, N content, and N location in the structure. In the best cases, the presence of these Ga(N)As spacer layers improves the PL properties, due to annealing, with a reduction in the emission wavelength blueshift by ～400 Å, a reduction of the decrease in the full-width at half-maximum (FWHM) by ～5 meV, and a threefold reduction of the increase in integrated intensity. It was also observed that relocating N from the quantum wells to the barriers produces a comparable emission wavelength both before and after annealing. Our results further show that the composition of incorporated N in the material is most influential during the stages of RTA in which relatively small amounts of thermal energy is present from our lower annealing times and temperatures. Hence, we believe a low thermal-energy anneal is responsible for the recovery of the plasma-related crystal damage that was incurred during its growth. However, the In composition in the quantum well is most influential during the latter stages of thermal annealing, at increased times and temperatures, where the wavelength blueshift was roughly independent of the amount of incorporated N. As a result, our investigations into the effects of RTA on the PL properties support other reports that suggest the wavelength blueshift is not due to N diffusion.     

Photophysics of the Lanthanide Complexes with Conjugated Carboxylic Acids by Low Temperature Fluorescent Spectroscopy

In the context, some lanthanide (Eu³⁺, Tb³⁺ and Sm³⁺) complexes with conjugated carboxylic acids (pyridine-carboxylic acids derivatives) have been synthesized and characterized. The low temperature fluorescent spectra for these complexes have been measured at nitrogen atmosphere (77 K), indicating that the central Ln³⁺ ions locate in an equivalent coordination environment with low symmetry for most of these lanthanide complexes belonging to dimeric or polymeric structure. Therefore, the electronic dipole transition (supersensitive transition) (⁵D₀ → ⁷F₂ for Eu³⁺, ⁵D₄ → ⁷F₆ for Tb³⁺, ⁴G_5/2 → ⁶H_9/2 for Sm³⁺) and magnetic dipole transition (⁵D₀ → ⁷F₁ for Eu³⁺, ⁵D₄ → ⁷F₅ for Tb³⁺, ⁴G_5/2 → ⁶H_5/2 for Sm³⁺) show the regular change in the corresponding split number of fluorescent spectra, which can be realized to predict the fine structure of lanthanide complexes.     

Mechanism of photoluminescence excitation of Mn<Superscript>2+</Superscript> ions in ZnS crystals

The mechanisms of photoluminescence excitation of Mn²⁺ ions in ZnS crystals have been investigated on the basis of complex analysis of the temperature dependences of the photoluminescence and photoluminescence-excitation spectra of ZnS:Mn crystals. The activation energy of a manganese luminescence center was estimated at E_a = 0.17 ± 0.05 eV. It is shown that E_a represents an energy band with a width ΔE_a = 0.1 eV, within which a manganese luminescence center can experience radiationless recombination. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 788–793, November–December, 2005.     

Effects of hydrostatic pressure and temperature on electronic band parameters in Al<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Ga<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>As

Influence of hydrostatic pressure and temperature on electronic band parameters for zinc-blende Al_xGa_1–xAs was investigated by means of pseudopotential calculations. The agreement between our results and the available experimental data is generally satisfactory. Our results showed that the effect of pressure leads to a decrease of the crossing point and the optical bowing parameter. However, the temperature effect was found to be insignificant on both crossing point and bowing parameter.