The microstructure of Cu films deposited by the self-ion assisted technique

The microstructures of Cu films deposited by the self-ion assisted, partially ionized beam (PIB) deposition technique under two different accelerating potentials, 0 KeV and 6 KeV, are compared. The 6 KeV film shows a bimodal (111) fiber and (100) fiber texture with an abundance of twin boundaries and a relatively large average grain size with a typical lognormal distribution. The 0 KeV film consists of small, mostly (111) oriented grains with islands of abnormally large (100) grains. The controlling factors for the abnormal growth of the (100) grains are discussed in relation to the observed microstructures, showing that all factors necessary for abnormal (100) growth are present in the films.     

Submillimeter Wave Quasioptical Isolators with a Semiconductor-Based Circular Dichroic Mirror

A quasioptical isolator is studied which takes advantage of using a circular dichroic mirror for the development of a most difference between the reflection coefficients of the orthogonal circularly polarized waves. The dielectric-semiconductor and semiconductor-metal versions of the circular dichroic mirror are examined. The test show that the isolator built around the ftoroplast/n-InSb mirror makes available the wave range 0.83–1.03 mm with forward loss 2.5–3.0 dB, reverse loss 15–21 dB, and VSWR 1.02–1.14, the longitudinal magnetic field is 1.3 kGs. The isolator with the n-InSb/metal mirror covers the 0.96–1.00 mm range and offers forward loss 2.5 dB, reverse loss 20–27 dB, and VSWR less than 1.2, with the longitudinal magnetic field 0.94 kGs. A possibility of the further advancement of the devices of this kind is shown.     

Formation of nitrogen-containing oligomers by methylglyoxal and amines in simulated evaporating cloud droplets

Reactions of methylglyoxal with amino acids, methylamine, and ammonium sulfate can take place in aqueous aerosol and evaporating cloud droplets. These processes are simulated by drying droplets and bulk solutions of these compounds (at low millimolar and 1 M concentrations, respectively) and analyzing the residuals by scanning mobility particle sizing, nuclear magnetic resonance, aerosol mass spectrometry (AMS), and electrospray ionization MS. The results are consistent with imine (but not diimine) formation on a time scale of seconds, followed by the formation of nitrogen-containing oligomers, methylimidazole, and dimethylimidazole products on a time scale of minutes to hours. Measured elemental ratios are consistent with imidazoles and oligomers being major reaction products, while effective aerosol densities suggest extensive reactions take place within minutes. These reactions may be a source of the light-absorbing, nitrogen-containing oligomers observed in urban and biomass-burning aerosol particles.     

Influence of Overheating and Cooling Rate on the Structures and Properties of Alloys of the Fe–B System

Materials Science - It is shown that the overheating of a melt by 150°K over the liquidus curve and a cooling rate of 102?104 °K/sec favor the formation of a homogeneous finely...     

Relationship between pectin sorption on a MA-40 anion-exchange membrane and its structural characteristics

The sorption of pectins of different origin on a MA-40 anion-exchange membrane has been studied. It has been revealed that the dependence of specific sorption on equilibrium pectin concentration is step-like. A relationship between the structural characteristics of the membrane and the concentration of pectin sorbed on it in the solution and the molecular weight of pectin has been determined. The sorption process has been found to be most intense in the region of small nanopores of the membrane. The possibility in principle of regenerating the membranes from the sorbed pectin molecules has been shown.     

Perfluorinated nanocomposite membranes modified by polyaniline: Electrotransport phenomena and morphology

This work summarizes results on the modification of perfluorinated sulfocationic membranes MF-4SC by in situ chemical polymerization of aniline. The investigation of transport properties of polyaniline/MF-4SC composite membranes after bulk modification - conductivity, diffusion and electroosmotic permeability, proton permselectivity - as well as porosimetry and polarization behavior is carried out as functions of aniline polymerization parameters and acid concentration. The fibrous-cluster model of a composite membrane is proposed for the estimation of transport and structural parameters, taking into account different mechanism of charge transfer in structural fragments of the composite. The atomic force microscopy images and curves of water distribution on the effective pore radii in the composite membranes testify to a morphological transition from the nano- to the microsize of polyaniline inclusions with increasing the aniline polymerization time. This effect is confirmed by the analysis of two-phase model transport and structural parameters. High values of the “true” proton transport numbers of composites are obtained and discussed. The dynamic hydration numbers of protons and chloride co-ions are estimated using the “true” transport numbers of protons and the electroosmotic coefficients of composites. The current-voltage curves of composite membranes in the “free standing” state after bulk and surface modification by polyaniline are investigated. The effect of stabilization of limiting current density is observed for MF-4SC membrane after bulk modification. The effect of current-voltage curves asymmetry is observed for different orientation of the polyaniline layer towards the current direction for an anisotropic composite membrane after surface modification.     

Femtosecond laser microstructuring in the bulk of diamond

In this paper we report the fabrication of graphitic microstructures in the bulk of diamond using 120-fs-laser pulses at 800 nm wavelength. Polished plates of single crystal diamond and optical quality polycrystalline CVD diamond were used as samples for 3D microstructuring. Under low fluence conditions and focusing a laser beam into the bulk of diamond plates, multipulse irradiation was found to result in the appearance and continuous growth of a laser-modified (graphitized) region from the focal plane towards the laser beam. Controlling the laser fluence and sample translation velocity (scanning beam velocity) allowed high-aspect-ratio ‘graphitic wires’ – microstructures of a few microns in diameter and several hundred micrometers in length – to be fabricated in the bulk of diamond. Physical processes responsible for the continuous growth of microscopic graphitic regions towards a laser beam are discussed. Results of comparative investigations of graphitic microstructures produced by laser pulses of different durations (120 fs and 300 ps) are presented to show the advantages of ultrashort laser pulses in 3D microstructuring of diamond.     

Adsorption processes in the technology of polymer composite materials with magnetic properties

The selection of a model of an adsorption solution was substantiated. Satisfaction of the Larionov criterion [3] indicates that the selected parameters of the adsorption phase do not contradict the physical picture of adsorption. The basic thermodynamic characteristics of adsorption of phenol-formaldehyde oligomer on the solid surface of ferromagnetic disperse fillers were calculated. The correlation of the limiting adsorption value, adsorption layer thickness, and adhesive strength in polymeric magnetic materials was demonstrated. Translated from Khimicheskie Volokna, No. 3, pp. 50–52, May–June, 1998.