Giant blue shift of photoluminescence in strongly excited type-II ZnSe/BeTe superlattices

A giant blue shift (≈0.5 eV) and a large decrease in the emission time of a spectral band corresponding to radiative recombination of spatially separated electrons and holes are observed in ZnSe/BeTe superlattices at high laser excitation levels. On the basis of numerical calculations, the observed defects are attributed to band bending arising in type-II structures at high carrier density. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 5, 351–356 (10 September 1997)     

Focusing of electrons reflected from a crystal with loss of energy

A study is made of the features arising in the spatial distributions of reflected electrons as a result of a focusing effect. Experiments are conducted on single-crystal Mo (100) with primary electron energies of 0.5–2 keV and detection of electrons which lose fixed amounts of energy up to 300 eV. An analysis of the data establishes the dependence of the electron focusing efficiency on the amount of energy loss. It is shown that when electrons are reflected with single losses through plasmon excitation, the magnitude of the effect is determined mainly by the average number of scattering atoms encountered by an electron along its path to the surface. When the energy losses are high, defocusing owing to multiple elastic and inelastic scattering of the electrons is found to predominate. Zh. Tekh. Fiz. 68, 128–133 (June 1998)     

Binding energy of silicon 2p electrons in iron silicides

Experimental data for the binding energies of Si 2p electrons in a number of stable and metastable iron silicides are analyzed and generalized. The silicides are applied on the Si(100)2 × 1 and Si(111)7 × 7 reconstructed single-crystal faces with solid-phase epitaxy. Core electron spectra are taken by means of high-energy-resolution photoelectron spectroscopy using synchrotron radiation. It is shown that the binding energies of Si 2p electrons in stable silicides, as well as in the silicon-iron solid solution, increase with increasing silicon content in them, since the role of interatomic relaxation in photoelectron excitation events grows feeble.     

Coherent control of harmonic generation in superlattices: single-mode response

We study the harmonic generation spectrum in a semiconductor superlattice (a quantum-dot array) at slow relaxation. The effect of a single-mode response in an alternating rectangular (meander) electric field is demonstrated: For certain values of field parameters, the extremely wide discrete output spectrum with slowly decaying tails (multiharmonic generation) shrinks to one single harmonic (single-harmonic generation). Similarly, the effect is manifested in the transient continuous spectrum by diminishing the divergencies (peaks) at all odd harmonics but one. Substantial control over the spectrum is demonstrated.     

Focusing of electrons reflected from layered crystal

The mechanism of the formation of the diffraction patterns upon inelastic reflection of mean-energy electrons from the VSe₂(0001) layered crystal has been investigated. It is found that the strong scattering of electrons by short atomic chains of the Se-V-Se layer triads leads to the weakening of electron focusing and the enhancement of diffraction scattering in deeper layers, which gives rise to the Kikuchi lines. It is demonstrated that, at an energy of 2 keV, the diffraction pattern is adequately described by the cluster model of single scattering. The atomic structure of thin near-the-surface layer of VSe₂ has been investigated by the computer simulation of experimental data.     

Influence of Nanoscale Titanium Dioxide Modifications on the Nano-Organization of Elastomers

Crystallography Reports - The diffraction patterns of fluorine rubbers ICF-26 and ICF-32 and vulcanizates based on ICF-32 with nanoscale titanium dioxide modifications are found to contain...