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Recent work on the photoluminescence (PL) properties of InAsP/InP nanowires are reported. InP nanowires were grown on <111> Si substrates by the Au-assisted vapor-liquid-solid process in a gas source molecular beam epitaxy system. InAsyP1-y segments were grown within the InP nanowires, creating single or multiple quantum dots structures. The quantum dot dimensions and composition were determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive x-ray spectroscopy (EDX). PL from the quantum dot structures could be tuned by the InAsyP1-y composition (y), or by the size of the quantum dot via the quantum confinement effect. Cathodoluminescence (CL) measurements confirmed localized emission from the quantum dots. To reduce detrimental surface states, the nanowires were passivated with an AlInP shell, which resulted in strong PL emission.

We developed a pulsed, continuously tunable laboratory laser source for the mid-infrared spectral range of 4.4–8 μm, which is characterized by the spectral linewidth of 0.4 cm^−1. The device is based on the stimulated backward Raman scattering in solid para-hydrogen at T = 4 K. It is pumped by a focused beam obtained from a commercial near-infrared optical parametric oscillator with output energy of ~20 mJ (7-ns pulse). Output energies range from 1.7 mJ at 4.4 μm to 120 μJ at 8 μm, which correspond to quantum efficiencies of 0.53 and 0.08, respectively. Spectra of NO, H_2O, and CH_4 molecules in the mid-infrared were recorded. The operation of the Raman cell pumped with 532-nm radiation was also studied.

The usage of non-paraxial elements, like a “fat” mirror cell or a divertor, is one of the techniques for stabilizing plasma in axisymmetric systems. The plasma equilibrium in such elements is studied in the paper. The calculation based on the Grad-Shafranov type equation has been done for plasma equilibrium under isotropic and anisotropic pressures in the configuration with a divertor, produced with the given external currents. The inverse variable technique is used in the problem with the fixed boundary surface. This approach is used, in particular, for calculating an equilibrium in the rippled field.

We have used a computer mathematically to experiment with and to formulate solutions for the problem of optimum control by means of quasiuniform heating of Foucault currents in cylindrical steel specimens.

Abstract:: The AM1 semiempirical numerical method combined with the geometry optimization procedure was used to study the energetics of active impurities (B, P) in substitutional positions at the Si(100)-2╳1 surface. It has been found that phosphorus prefers to be in the first layer (in dimers). Boron has the lowest energy in the second layer. Energy profits, counting from the fourth bulk-like layer, for B and P are 1.33 eV and 0.56 eV, respectively. Comparing of the P-Si and P-P dimers energetics has shown that P-Si dimers are more preferable energetically.

We have performed a first-principles local-density cluster investigation of nanoscalep-Si/n-Si junctions. Al and P atoms were used as dopants and Al-P distances were of order a few A˚ngstroms. The thermoemission current-voltage characteristics were calculated in addition to the electronic structure. It was shown that a rectifying nanoscalep-njunction can be formed in silicon if the distance between donor and acceptor atoms is not too small (about 1nm).

Using the local-density approximation method we have investigated a cluster model of the Al/Si(111) interface. P atoms were placed in the fifth silicon double-atomic layer (DAL) counting from the interface. The second DAL was doped with either Ga or As. The Schottky barrier height was found to be 0.75 eV at the Al/Si(intrinsic) system and 0.73 eV at the Al/Si(P-doped) case. The additional doping of the near-interface layer by Ga increased the barrier to 0.90 eV while the As doping decreased it to 0.5 eV.

The KEDR collaboration has taken data for Rmeasurements at energies 3.1–3.7 GeV. Preliminary results from the analysis of these data are presented.

Using ab initiolocal-density approach we have studied the electronic structure of the free n-fold SiO2rings as well as the rings placed upon the surface of the silicon cluster. For the free planar rings the best agreement of theoretical results and the experimental ultraviolet photoemission spectrum of the amorphous silica was obtained for the 6-fold ring. The interaction of the 6- and 4-fold planar SiO2rings with the silicon surface change the electronic structure of the silica particle very weakly. The electronic structure of the 3-fold planar ring, which contacted the silicon surface undergoes a significant reconstruction.

We consider several classes of analytic parametrizations of hadronic scattering amplitudes, and compare their predictions to all available forward data (pp, pp, πp, Kp, γp, γγ, Σp). Although these parametrizations are very close for √s ≥ 9 GeV, it turns out that they differ markedly at low energy, where a universal Pomeron term ∼ ln2 s enables one to extend the fit down to √s = 4 GeV. We present predictions on the total cross sections and on the ratio of the real part to the imaginary part of the elastic amplitude (ϱ parameter) for present and future pp and pp colliders, and on the total cross sections for γp → hadrons at cosmic-ray energies and for γγ → hadrons up to √s = 1 TeV. [Copyright &y& Elsevier]