Ionization potential of a metal cluster containing vacancies

A consistent procedure for determining the ionization potential of a large metal cluster of radius R _{N, v} , consisting of N atoms and N _v vacancies, is proposed. The perturbation theory in small parameters R _v /R _{N, v} and L _v /R _v (Rv and L _v are average distance between vacancies and the length of electron scattering on vacancies, respectively) is constructed in the effective-medium approximation for the electron ground state energy. The effective vacancy potential profile, the electron scattering phase and length are calculated by the Kohn–Sham method for a macroscopic metal in the stable jelly model. The obtained analytical dependences can be useful to analyze the results of photoionization experiments and to determine the size dependence of the vacancy concentration, including that near the melting temperature.     

Start of Electron Cooling System for the NICA Booster

In order to achieve the required beam parameters in the NICA booster, the electron cooling system (ECS) was designed and manufactured at the Institute of Nuclear Physics (INP), Novosibirsk. In 2017, the system was shipped to JINR and its assembly and commissioning started. A specific feature of this system is that, for the first time ever, the electron cooling method with a magnetized e-beam is applied at the superconducting synchrotron; this imposes some additional requirements for the design and start of the ECS, operating at room temperature. This paper describes the main steps of the ECS assembly and start at the straight section of the booster, including mounting mechanical, electrical, and plumbing systems (water, electricity, air, and oil system) and geodetic works on installing the system on site. The measured magnetic field homogeneity for the straight solenoid is given. The assembly of vacuum and magnet systems takes several steps because of the ECS design features. At the final assemblage stage of the vacuum system, the vacuum chamber is baked up and the bulk getters and the cathode of the electron gun are activated. Upon completing assembly and testing the high voltage system, the E-beam is conducted from the gun to the collector.     

Low temperature Fourier transform infrared spectra and hydrogen bonding in polycrystalline uracil and thymine

The FTIR spectra of pure NH and isotopically diluted (NH/ND and ND/NH) polycrystalline uracil and thymine were measured in the range 4000-400 cm(-1) at temperatures from 300 to 10K. For the first time, the essentially narrow bands corresponding to the uncoupled stretching (nu(1)) and out of plane bending (nu(4)) NH proton modes of uracil and thymine were observed in the solid phase. It was found that in the nu(4) region the spectra reveal more details on the H-bond interactions present in both solids than in the nu(1) range. The frequencies of the various bands observed in both spectral regions were used for estimation of the H-bond energy, using empirical correlations between this property and both the red shift of nu(1) and the blue shift of nu(4) that occur upon crystallization due to the establishment of the H-bonds. The results are compared with known thermodynamic, structural and theoretical data. The IR data also suggest that the H-bond networks of both crystals contain, besides the two NH...O=C bonds revealed by X-ray experiments, additional types of H-bonds, which do not show long range periodicity and, thus, cannot be detected by the conventional structural methods. The assignment of some other bands in the spectra of both substances was also reviewed.     

Alloying during codeposition of copper and tin out of silicofluoride electrolytes

A technique for obtaining binary Cu-Sn alloys containing 20–35 mol % Sn is proposed. The technique—the electrochemical deposition out of silicofluoride electrolytes—ensures a high deposition rate of coatings (25–50 μm h^?1). The formation of intermetallic compound Cu₁₀Sn₃ is found to occur at a high current density, in conditions of the tin reduction depolarization and the copper reduction superpolarization. The alloys consist of submicron grains. Apart from crystalline Cu₁₀Sn₃, they include x-ray-amorphous tin (2–12 mol %) and tin oxides (≤1–3 mol %). The alloys feature high hardness (4200 MPa), corrosion resistance, and solderability.     

Low-temperature Fourier transform infrared spectra and hydrogen bonding in polycrystalline L-alanine

The 400-4000 cm(-1) FTIR spectra of pure NH and isotopically substituted (10 and 90% doped ND/NH) polycrystalline L-alanine were recorded in the temperature range 10-300 K. The observed temperature dependence and isotopic shifts behavior enabled to identify, in the spectra of the doped crystals, three well-separated bands ascribable to either the NH or ND stretching vibrations associated with the three different types of hydrogen bonds existing in the crystal. The observed red shifts of these bands relative to the frequency of a reference "free" NH (or ND) stretching mode were found to correlate well with the H-bond distances found in the crystal and provide an indirect way of estimating the enthalpies associated with each type of H-bond found in the crystal. In the low-frequency deformation and torsional spectral region (below 2000 cm(-1)), several bands, which were found to be affected by isotopic substitution, were identified as belonging to the NH3(+) group. Several bands show splitting at low temperatures, indicating the occurrence of a significant reorganization in the crystal structure, which with all probability results mainly from changes in the proton positions. Finally, the literature assignments of the IR spectra of both crystalline NH3(+) and ND3(+) L-alanine were revised taking into consideration their temperature dependence and behavior upon deuteration.     

Molecular structure, vibrational spectra and photochemistry of 2-methyl-2H-tetrazol-5-amine in solid argon

In this work, the molecular structure, infrared spectrum and UV photochemistry of 2-methyl-2H-tetrazol-5-amine (2MTA) isolated in solid argon (10 K) were investigated. The experimental studies were supported by extensive DFT(B3LYP)/6-311++G(d,p) calculations. The infrared spectrum of matrix-isolated 2MTA was fully assigned and correlated with structural properties. Taking into consideration the observed frequency of the NH2 wagging mode, it is suggested that, in the matrixes, the amine group becomes slightly more planar than in the gas phase, due to matrix-packing effects. In situ UV irradiation (lambda > 235 nm) of the matrix-isolated 2MTA monomer is shown to induce three main primary photochemical processes: (1) tautomerization to mesoionic 3-methyl-1H-tetrazol-3-ium-5-aminide; (2) nitrogen elimination, with production of 1-methyl-1H-diazirene-3-amine; (3) ring cleavage leading to production of methyl azide and cyanamide. Following the primary photoproducts, secondary reactions were observed, leading to spectroscopic observation of methylenimine and isocyanidric acid.     

Simple and efficient synthesis of substituted 1H-indazoles

3-Aryl-5-aroylindazoles were prepared by a simple two-stage protocol from 3,5-diaroyl-2,6-dimethylpyridines.     

Cascade Transformer Based on the Volume Coil for Power Transmission under High Voltage

The use of an electronic cooling system at the High Intensity heavy ion Accelerator Facility (HIAF) accelerator complex, which is being developed at the Institute of Modern Physics (China), to improve the efficiency of ion injection into the accelerator and reduce the spread of ion pulses in the beam has been proposed. Electron cooling of the ion beam was carried out due to the interaction of ions with a continuous electron beam with a current of up to 3 A, energy of up to 450 keV, and energy stability at the level of 10^–4 or better. The electron beam energy recuperation was carried out at the expense of a power source with a power of 5–15 kW, which was located at the top of a high-voltage column—a high-voltage terminal. The operation of a prototype of power transmission system, which was based on a cascade transformer with a volumetric coil, has been considered. Such a transformer has a relatively low scattering inductance, which can significantly reduce the number of capacitors to compensate for it. It has been shown that this design made it possible to transfer power of up to 40 kW at small dimensions of the transformer and heat dissipation in it was not more than 10 kW.     

Electron cooling experiments in CSR

The six species heavy ion beam was accumulated with the help of electron cooling in the main ring of Cooler Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR). The ion beam accumulation dependence on the parameters of cooler was investigated experimentally. The 400 MeV/u ¹²C⁶⁺ and 200 MeV/u ¹²⁹Xe⁵⁴⁺ were stored and cooled in the experimental ring CSRe, and the cooling force was measured in different conditions.

     

An approximate treatment of scattering based on the delta boundary operator

The development of a scheme to treat two-dimensional electromagneticscattering by electrically large, perfectly conducting bodiesis described. It incorporates the effects of surface curvatureand non-local phenomena and has the potential to provide thebasis for a general technique yielding more accurate predictionsthan the widely used physical optics method.