Diffusion of metal vapors in gases and the transport properties of vapors

Test data on the diffusion of metal vapors in gases and on the viscosity of the vapors are generalized. The ionization energies and the polarizabilities are chosen as the scales.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 42, No. 6, pp. 930–937, June, 1982.     

A time-dependent density functional theory study on the absorption spectra of Cu(n) clusters

The structures and absorption spectra of neutral Cu(n) (n = 3-9) clusters, are studied in the framework of the time-dependent density functional theory (TDDFT) using all-electron calculations. The obtained ground state structures are respectively planar for Cu(n) (n = 2-6) and 3-dimensional for Cu(n) (n = 7-9). The calculations of transition energies, oscillator strengths and dipole moment of absorption spectra have been calculated and investigated in a large energy interval, which allow us to determine the role of d electrons. The spectral analysis shows that 3d electrons are responsible for spectrum behavior of Cu(n) (n = 3-8) in addition to the contribution of 4s electrons, while only 3d electrons are primarily responsible for spectroscopic patterns of Cu9. The results are entirely different from the absorption spectra of Ag(n) with the same number of atoms.     

Effect of heat treatment on the infrared absorption spectra of Sr-Na borosilicate glass

Internal modes of vibrations are studied here at different temperatures (27–800°C) and in the frequency range 200–4000 cm^–1 through heat treatment. The baseline method was used. The strong bands of SiO₄ tetrahedra in this glass show an increase in absorbance at high temperature (600–800°C). The deformation of SiO₄ tetrahedra is investigated. This is found to depend on the ionic radius of the divalent metal oxide introduced, and the coordination number of the cation. Also from a study of the temperature dependence of the relative integrated intensity of the modes 600–800 and 850–1450 cm^–1, the relaxation time and rotational energy barrier of the glasses selected indicate that the glassy phases are transformed to crystalline phases at 500°C.     

The physical nature of the optical emission and absorption accompanying explosive decomposition of heavy metal azides

The kinetics and spatial characteristics of the optical emission and absorption have been studied in the course of explosive decomposition of silver azide initiated by a pulsed electron beam. The emission and absorption observed after the induction period reflect the process of formation and expansion of the products of chemical decomposition of silver azide.     

Some effects of the addition of iron oxide and of annealing on the optical and infrared absorption spectra of sodium tetraborate glasses

The optical and infrared absorption spectra of sodium tetraborate glasses containing iron oxide have been studied as a function of iron content. It was found that the addition of iron oxide shifts the optical absorption edges towards lower energies and introduces a new absorption band as compared with the optical absorption spectrum of pure sodium tetraborate glass. The addition of iron does not introduce any new absorption band in the infrared spectrum of pure sodium tetraborate glass. The measurements were made on unannealed samples and samples annealed at different temperatures.     

Measurement of high-temperature accommodation coefficients for alkali metal vapors on nickel

Measurements on the temperature step have given the accommodation coefficients for cesium, rubidium, and sodium vapors on nickel for the range 685–1095°K.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 29, No. 4, pp. 606–608, October, 1975.     

Correlation between the magnetic properties and the chemical shifts in x-ray absorption spectra of some transition metal compounds

Studies on the chemical shifts of the K x-ray absorption discontinuities of some transition metal compounds recently conducted in our laboratory have revealed that the ΔE vs q curves do not pass through the origin. For such systems one obtains an intercept on the ΔE axis, which seems to depend uponn _d , the number of unpairedd electrons. As is well-known the magnetic properties of the compounds of transition metal elements are governed by thed electrons. It is shown that the magnetic properties of the transition metal compounds may be correlated with x-ray absorption spectra.     

Static and dynamic properties of high-density metal honeycombs

Metal honeycombs are commonly used to absorb energy in applications involving impact because of their high-energy capacity to weight ratio. The energy capacity of a material will be affected by any strain-rate effect in the material; thus knowledge of this property is necessary for design purposes. The materials studied in this work were a thick-walled aluminum and stainless-steel honeycomb. A method of testing the specimens in a state approximating uniaxial strain was developed for the large compressive deformations required with honeycombs, and used for both static and dynamic tests. For the dynamic tests, a gas gun was used to propel projectiles into fixed specimens of the test materials, and measurements of the force at the fixed ends of the specimens were used to determine the energy absorption properties of the materials. Initial strain rates to about 2000/s were obtained. Both materials showed a strain-rate effect.     

Photo EMF observed upon the laser resonance excitation of sodium vapors

A method of the direct light-to-electric energy conversion in photoplasma is proposed. The photo emf was observed in experiments on the pulsed laser excitation of sodium vapors. It is demonstrated that the separation of charged particles in the plasma is caused by the inhomogeneous distribution of resonance-excited atoms in the direction of optical excitation.     

Effect of thermal stabilization on the optical absorption of some transition metal ions in glass

The optical absorption of a 30Na₂O, 70SiO₂ glass containing iron, chromium or cerium has been studied after thermal stabilization at various temperatures around the transformation range of the glass. The optical absorptions due to iron(II), iron(III), cerium(III) and cerium(IV) have been found to increase with increasing stabilization temperature; the optical absorptions due to chromium(III) and chromium(VI) do not change significantly with stabilization temperature. The changes in optical absorption due to stabilization at different temperatures have been found to be reversible and reproducible. It has been argued that as the equilibrium volume of a given mass of glass increases with increasing stabilization temperature, and as the ligand field strength surrounding the transition metal ion does not increase due to this enlargement of volume while the optical absorption increases, the high temperature stabilization of a glass probably increases some local randomness of structure (creating extra distortion of the transition metal complex) and does not cause an uniform volume expansion of the glass.     

基于HITEMP数据库的分子吸收光谱高精度快速建模方法

为解决高温环境下分子吸收光谱精确计算的时间复杂性,满足宽光谱测量领域对理论吸收光谱计算的需求,本研究利用Python语言以逐线计算为基础,结合线型函数的简化、线翼截止准则和谱线数据库的优化,建立了基于高温分子吸收参数数据库(High-Temperature molecular spectroscopic absorption parameters data-base,HITEMP)的分子吸收光谱精确快速计算模型。以Hartmann-Tran线型函数作为吸收光谱标准线型编写部分相关二次速度依赖硬碰撞函数(partially-Correlated quadratic-Speed-Dependent Hard-Collision Profile,p Cq SDHC),结合复概率函数(Complex Probability Function,CPF)简化模型实现了线型函数的精确快速计算,相较于理论计算模型计算速度提高了20倍。按照光谱计算残差在10^-5量级确定了固定波数截断结合谱线半宽等倍数截断的线翼截止准则。以阈值线强度10^-25 cm^-...     

Formation of Mn-oxide clusters in Mn-implanted SiO2 probed by soft X-ray emission and absorption spectroscopy

Mn⁺-implanted a-SiO₂-samples were studied with the help of soft X-ray emission and absorption spectroscopy (Si L_2,3 3d3s → 2p_3/2,1/2 and Mn L_2,3 3d4s → 2p_3/2,1/2 emission transitions) using synchrotron excitation. The samples were obtained using a pulsed ion source (ion beam current density ∼2-7 mA/cm², E_impl. = 30 keV, ion fluence ∼2 × 10¹⁷ cm⁻², pulse duration 400 μs) without thermal annealing. It was established that Mn-ion provides a formal valence state 2+, so arranging in implanted a-SiO₂ the low-sized MnO antiferromagnetic clusters probably of crystalline type. The data obtained well coincides with the electronic spin resonance results reported earlier.     

Absorption and emission spectra of the YBCO laser plume

The plasma produced during laser ablation deposition of thin film YBCO has been studied by optical emission spectroscopy. There is evidence of increased YO band emission in the range 590–625 nm as the ambient oxygen gas pressure confining the plume is increased in the range 30–200 m Torr. Temporal profiles show that close to the target the plume is insensitive to ambient oxygen pressure. It is deduced that the optical emission here is excited by electron impact excitation. Further away from the target there is evidence that two distinct processes are at work. One is again electron excitation; the emission from this process decreases with distance because the expanding plume cools and collisions become less frequent in the expanding gas. The second is driven by oxidation of atomic species expelled at high speeds from the target. The main region of this activity is in the plume sheath where a shock front ensures heating of ambient O₂ and reaction of monatomic plasma species to form oxide in an exothermic reaction. Spatial mapping of the emission demonstrates clearly how increasing oxygen gas pressure confines the plasma and enhances the emission intensity from the molecular YO species ejected from the target in a smaller region close to the target. Ba⁺ is observed as a dominant species only very close to (within 1 mm of) the target. Absorption spectra have been taken in an attempt to examine ground state and cool species in the plume. They reveal the quite surprising result that YO persists in the chamber for periods up to 1 msec. This suggests an explanation for the recent report of off-axis laser deposition in terms of simple condensation. Previously, quasi-ballistic transfer of material from target to substrate has been considered the only significant process.     

Faraday rotation density measurements of optically thick alkali metal vapors

We investigate the measurement of alkali number densities using the Faraday rotation of linearly polarized light. We find that the alkali number density may be reliably extracted even in regimes of very high buffer gas pressure, and very high alkali number density. We have directly verified our results in potassium using absorption spectroscopy on the second resonance (4²S→5²P).