Theoretical study of low-lying electronic states and emission spectra of the excimer ions NaHe and NaNe

Ab initio CASSCF calculations using the Gaussian basis set aug_cc_pVTZ developed by Dunning et al. specifically for calculations at the post-HF level was carried out for excimer NaHe⁺ and NaNe⁺ ions in order to determine spectroscopic characteristics and radiation lifetimes of their low-lying excited electronic states. The computed emission spectra of these were shown to be in good agreement with the experimental ones observed recently by Hammer et al. (Hyperfine Interactions 88 (1994) 151). Contrary to the earlier popular opinion, all excited electronic states of these ions, correlating with the limit Rg⁺+Na, and not just the radiating singlet states turn out to be bound. It was shown that under the conditions of an experiment similar to the one performed by Hammer et al., the excited triplet NaHe⁺(1³Σ⁺) states can decay as a result of their interactions with a high-energy Ar⁺ beam. This decay has to be accompanied with the formation of the ions He⁺, which in turn can interact with sodium atoms to yield the radiating NaHe⁺(2¹Σ⁺) states again and, thus to maintain the emission observed in the experiment.     

Semiempirical calculations of electronic spectra of Ru (II) and Ru (III) compounds in restricted active space CI approximation

Calculations of spectral characteristics of seven Ru(II) and Ru(III) complexes were performed. The excitation energies of the compounds studied in this work are in agreement with experimental data. Some regularities in the structure of excited states were demonstrated. Our results show that the use of the quantum chemical methods in which the reorganization and solvent effects are included explicitly can give reliable information concerning electronic structure and spectra of complex transition-metal compounds. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 853–860, 1997     

Axially Symmetric Compact Range Reflectors: Application of the Analytic Regularization Method

An axially symmetric compact range reflector with a blended rolled edge was analyzed and optimized in a rigorous formulation of the diffraction problem. The corresponding boundary-value diffraction problem is solved with the analytic regularization method, which reduces the problem to an operator equation of the second kind, thus guaranteeing a numerically stable and effective solution. The distribution of the surface density and the fields at the aperture and in the near-field zone were obtained and analyzed for different types of the reflector-edge curvature. In addition, a “blending function” was used that esures an infinitely smooth contour across the junction between the paraboloid part of the reflector and its rolled edge. The procedure for determining the optimal edge is carried out in the rigorous formulation of the diffraction problem by minimizing the deviation from a plane wave.     

Mesoscopic surface folding in EK-181 steel polycrystals under uniaxial tension

The work is experimental and theoretical study of folded structures formed on free surfaces of polycrystalline materials under uniaxial tension. General mechanisms by which the folded deformation relief develops are demonstrated with the example of EK-181 steel. Numerical simulation shows that the polycrystalline structure of the material can be a condition responsible for local curvature of its initially flat surface and hence for periodic distribution of normal tensile and compressive stresses.     

A Method for Measuring Surface Relief in the Study of Strain Processes and Estimation of State of Materials under Loading

The paper presents a method and a device for surface-relief measurements in the study of plastic deformation at the meso- and macroscale levels, with the results to be used in nondestructive testing of materials. A block diagram of the computer-controlled system for measuring surface relief of loaded materials is described whose operation principle relies on a direct method of measurements with a commercial roughness indicator. Major technical data of the automated system are given and causes for measurement uncertainties are analyzed. Typical surface relief distribution patterns obtained with the system are reported.     

Effect of the Polyphosphate/Me Molar Ratio in an Aqueous Electrolyte on the Composition of Anodic-Spark Layers at Aluminum Alloys

The manner in which the molar ratio n = [sodium polyphosphate]/[Me cation] in aqueous electrolytes is related to the thickness h and the element content (EC) of anodic layers formed on aluminum and its alloys during electric microbreakdowns (sparks, microarcs) is established. The polyphosphate structure, the electrolyte pH, and the nature and charge of Me cation do not affect dependences of EC and h on n in the case of Mn(II), Pb(II), Mg(II), Zn(II), Ni(II), Y(III), and Eu(III). The film growth mechanism changes with n. The incorporation of P, Me(II), or Me(III) is due to thermolysis of precipitate from electrolyte containing hydrated polyphosphates of Me(II) or Me(III), the thermolysis occurring at the anode under the action of electric breakdowns.     

Effect of dopants and interlayers on the growth of thin insulating films

Surface morphologies of thin dielectric films deposited on gallium arsenide substrates are studied by atomic force microscopy (AFM). The quasi-periodic mesostructure with a corrugated configuration is found to form during the deposition process. A special dopant and thin interlayer at the film–substrate interface are used to decrease the surface roughness. The corrugated Si_xN_yO_z–SiO₂ film surface disappears by introducing Se atoms into the subsurface layer of the semiconductor. The root-mean-square roughness and the fractal dimension techniques are used for the numerical characterization of the surface morphologies of thin insulator films.     

Electronic structure and fluorescence spectrum of the HeO+ cation

Quantum-mechanical calculations of the potential curves of the HeO⁺ ion are preformed which correlate with four lower dissociation limits and indicate the excimer type of the ion. The transition dipole moments of the 2²Σ^?→1²Σ^? and 2⁴Σ^?→1⁴Σ ^? transitions are calculated. The energies and radiative lifetimes of vibrational levels are determined and structural and spectroscopic constants of the states 1²Σ^?, 2²Σ^?, 1⁴Σ^?, and 2⁴Σ^? are calculated. The fluorescence spectrum corresponding to the 2²Σ^?→1²Σ^? and 2⁴Σ^?→1⁴Σ ^? transitions is also calculated. The possibility of lasing at these transitions is discussed.     

Optical Properties of ZrO2–Containing Anodic Coatings on Aluminum

Anodic oxide coatings (AOC) formed at the potentials of spark breakdowns in aqueous solutions of potassium hexafluorozirconate (K₂ZrF₆) contain up to 36 wt.% of Zr. The modification of ZrO₂ in AOC is tetragonal. The reflection coefficients of AOC have been measured in the range 430–670 nm. After UV irradiation for a few hours the reflection coefficient decreases by several percent. The treatment of AOC in a solution containing F^– and [Fe(CN)]^3– ions leads to a change in the aluminum and zirconium concentrations in the surface layer and to an increase of the AOC reflectivity.