A 50% beam splitter for s-polarized light in the 700-to 900-nm range

A 50/50 beam splitter for s-polarized light in the 700-to 900-nm range on the basis of refractory oxides was synthesized and studied.     

Memristor effect on bundles of vertically aligned carbon nanotubes tested by scanning tunnel microscopy

We report on the results of experimental study of an array of vertically aligned carbon nanotubes (VA CNTs) by scanning tunnel microscopy (STM). It is shown that upon the application of an external electric field to the STM probe/VA CNT system, individual VA CNTs are combined into bundles whose diameter depends on the radius of the tip of the STM probe. The memristor effect in VA CNTs is detected. For the VA CNT array under investigation, the resistivity ratio in the low- and high-resistance states at a voltage of 180 mV is 28. The results can be used in the development of structures and technological processes for designing nanoelectronics devices based on VA CNT arrays, including elements of ultrahigh-access memory cells for vacuum microelectronics devices.     

Optimization of the structure of an optical fiber polarizer with a metal film at a wavelength of 980 nm

The dependence of the extinction ratio of a 980-nm fiber polarizer with an Al film on the thickness of magnesium fluoride buffer layer has been experimentally and theoretically investigated. At the optimal thickness of the buffer layer, h _b = 0.078 (normalized to the wavelength), extinction ratios of 23 and 41 dB were obtained for polarizers having fiber shell residual layers of 2.01 and 1.607 μm, respectively. The optimal thin-film structure is determined, which will make it possible to design polarizers with extinction ratios up to 100 dB.     

Intensification of gas-liquid processes in tubular turbulent apparatus

The fundamental aspects of intensification of the mass transfer in gas-liquid flows in tubular turbulent apparatus are revealed, and dependences of the gas absorption rate on the reactor geometry and method of reagent introduction are considered for the example of dissolution of atmospheric oxygen in water.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 11, 2004, pp. 1840–1843.Original Russian Text Copyright © 2004 by Zakharov, Minsker, Shevlyakov, Berlin, Aleksanyan, Rytov, Konoplev.     

Reaction of sulfolene oxides with thiocyanates

The reaction of oxides of sulfolene and its methyl derivative with potassium and sodium thiocyanates was studied. It is shown that under the influence of potassium thiocyanate these oxides undergo isomerization to the corresponding unsaturated alcohols. In the presence of sulfuric acid, however, the oxides react with sodium thiocyanate to give addition products, viz., hydroxythiocyanatosulfolanes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1333–1334, October, 1982.     

Approximation of continuous set-valued maps by constant set-valued maps with image balls

It is shown that the problem of the best uniform approximation in the Hausdorff metric of a continuous set-valued map with finite-dimensional compact convex images by constant set-valued maps whose images are balls in some norm can be reduced to a visual geometric problem. The latter consists in constructing a spherical layer of minimal thickness which contains the complement of a compact convex set to a larger compact convex set.     

Excitation-energy relaxation in photochromic indoline spiropyranes

Wave functions derived by CNDO/S have been used to calculate rate constants for excited-state deactivation in products from the direct photocoloration of indoline spiropyranes: unsubstituted, 6-methoxy, and 6-nitro. The rate constants have been compared for the radiative and radiationless deactivation of the excited S₁ state, which serves to identify the main relaxation channels in these photochromic compounds. The Wiberg indices for the bonds in the pyrane ring for various excited states define the photochemically active state involved in the photochromism. The multiplet structure in a channel for the most effective coloring is dependent on the electronic type of the substituent in position 6 in the chromene moiety.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, No. 4, pp. 420–427, July–August, 1989.     

Calculation of the parameters of the X-ray diffraction station with adaptive segmented optics on the side beam from the wiggler of the Sibir’-2 storage ring

The mounting of an X-ray diffraction station on the side beam of a 19-pole superconducting wiggler makes it possible not only to use the central synchrotron radiation beam with a wavelength of 0.5 ?, but also to solve problems requiring softer X rays at a synchrotron radiation (SR) intensity exceeding that for the beams from the bending magnet. A numerical simulation of the formation of photon beams from a source and their transmission through the elements of the station (and through the station as a whole) allows one to calculate the parameters of the station, compare it with the existing analogs, determine its potential and actual efficiency of its elements, and estimate the adjustment quality. A numerical simulation of the SR source on the side beam from the wiggler and the focusing channel (segmented condenser mirror, monochromator with sagittal focusing by the segmented second crystal, and segmented focusing mirror) has been performed. The sizes of the focus and the divergence of rays in it are determined with allowance for the finite sizes of segments. The intensity of radiation with a wavelength ?? = 1.0 ? in the focus is determined taking into account the loss in the SR extraction channel and in the focusing channel. The values of the critical wavelength for the side beam from the wiggler and the wavelength resolution are calculated. The intensities in the X-ray diffraction pattern and its angular resolution are found.