Experimental investigation and calculation of the spectral dependence of the absorption coefficient of single-layer epitaxial HgCdTe structures

The absorption coefficient of HgCdTe structures grown by the methods of liquid-phase epitaxy (LPE) and metalorganic chemical vapor deposition (MOCVD) is studied and calculated. The experimental data are compared to a theoretical absorption spectrum model, which is based on the fundamental absorption effect and the general theory of direct interband optical transitions, as well as other empirical dependences. The Fermi level shift in the studied HgCdTe structures and the slope of experimental absorption characteristics are calculated.     

Analysis of the spatial distribution of the spectral photosensitivity of focal plane arrays

Spectral responses of all elements of a focal plane array (FPA) have been analyzed. Differences in the received spectral responses of adjacent elements have been revealed. Regularities of variation in the right boundary of the spectral sensitivity have been found. The obtained data can increase the accuracy of developed and manufactured FPAs.     

A spectrophotometric study of the reduction of Pu(VIII) and Pu(VII) in alkaline solutions

The reduction of Pu(VIII) with water in ozonized 15 and 6 MNaOH solutions after termination of the ozone bubbling was studied by spectrophotometry. Kinetic curves reflecting the whole set of processes that occur in NaOH solutions of different concentrations were obtained. Calculations performed with the experimental curves made it possible to construct the kinetic curves describing the behavior of plutonium in higher oxidation states in solution and to obtain the individual absorption spectra of Pu(VII) and Pu(VIII). The processes occurring in ozonized solutions of Pu(VI) in 6 and 15 M NaOH after termination of the ozone bubbling were found to occur by different mechanisms, yielding in 4 days Pu(VI) and Pu(V), respectively.     

Evaluating the quality of caprolactam from toluene

Conclusions -- It has been found that the standard indices are necessary but not sufficient for a complete evaluation of the quality of caprolactam intended for the preparation of fibre-forming polycaproamide.-- The preferability of using a spectrophotometric method involving a color reaction withp-dimethylaminobenzaldehyde to evaluate the content of undesired admixtures of carbonyl compounds not regulated by the All-Union State Standard in caprolactam has been demonstrated.Translated from Khimicheskie Volokna, No. 5, pp. 51–54, September–October, 1990.     

Using thermionic nuclear power systems with a thermal reactor for interorbital space flights

Conclusion The use of a thermionic NPS with a thermal reactor in space technology to supply power to the RMPS offers broad possibilities for interorbital delivery of payloads while using comparatively cheap launch rockets to place spacecraft in a fixed orbit. The flight time from a fixed to a geostationary orbit ranges from several months to half a year, and the mass of the payload in a geostationary orbit for optimal RMPS parameters may reach 7–8 tons (not counting the mass of the NPS).It should be noted that after the flight is completed, the NPS can serve as a source of electrical power for spacecraft in geostationary orbit.Red Star Scientific-Production Organization. Translated from Atomnaya Énergiya, Vol. 70, No. 4, pp. 221–224, April, 1991.     

Characterization of glassy materials for immobilization of radioactive waste with a high iron oxide content

The influence of the content of oxides in the simulated high-level wastes on the phase composition, the structure, and the water resistance of borosilicate-based glassy materials for immobilization is investigated. An increase in the waste oxide content from 45 to 65 wt % leads to an increase in the fraction of the crystalline phase of the magnetite-type spinel from 3–5 to 20–22 vol %. The glassy materials are characterized by a low leaching rate of the main waste components in water. A considerable increase in the leaching rate of sodium ions and, to a lesser extent, aluminum and uranium ions is observed for the glassy materials containing waste oxides at a content of 55 wt % and more due to the depolymerization of the structural glass network. Under the same conditions, the leaching rate of iron does not increase noticeably because of the high resistance of the iron-containing spinel to water.     

Contact effects in graphene nanoribbon transistors

The effects of the various contact types and shapes on the performance of Schottky barrier graphene nanoribbon field-effect-transistors (GNRFETs) have been investigated using a real-space quantum transport simulator based on the NEGF approach self-consistently coupled to a three-dimensional Poisson solver for treating the electrostatics. The device channel considered is a double gate semiconducting armchair nanoribbon. The types of contacts considered are (a) a semi-infinite normal metal, (b) a semi-infinite graphene sheet, (c) finite size rectangular shape armchair graphene contacts, (d) finite size wedge shape graphene contacts, and (e) zigzag graphene nanoribbon contacts. Among these different contact types, the semi-infinite graphene sheet contacts show the worst performance because of their very low density of states around the Dirac point resulting in low transmission possibility through the Schottky barrier, both at ON and OFF states. Although all other types of contacts can have significant enhancement in I ON to I OFF ratio, the zigzag GNR contacts show promising and size invariant performance due to the metallic properties.