Resonant diffraction of synchrotron radiation in rubidium dihydrophosphate crystals

Purely resonant Bragg reflections 006, 5$ \bar 5 $ \bar 5 0, and 666 in a rubidium dihydrophosphate (RbH₂PO₄) crystal at the K edge of rubidium have been experimentally and theoretically investigated. These reflections remain forbidden when the resonant dipole-dipole (E1E1) contribution to the resonant atomic factor is taken into account; they may be due to the dipole-quadrupole (E1E2) transitions as well as to the anisotropy atomic factor, which is caused by thermal atomic displacements (thermally induced contribution) and/or local jumps of hydrogen atoms. A numerical simulation showed that, at room temperature (experimental conditions), the thermally induced contribution to the “forbidden” reflections is dominant.     

Source of Indistinguishable Single Photons Based on Epitaxial InAs/GaAs Quantum Dots for Integration in Quantum Computing Schemes

JETP Letters - The characteristics of single photons emitted by columnar microstructures based on epitaxial microcavity heterostructures with distributed Bragg reflectors, which include...     

Chemical investigation ofHippophaë rhamnoides. I. The main components of the unsaponifiable part of an extract of the fruit pulp

It has been established that the sterol fraction of the unsaponifiable part of a pentane extract of the fruit pulp of common sea buckthorn contains not only sterol but also triterpene alcohols and higher fatty alcohols. β-Sitosterol, 24-methylene-cycloartanol, citrostadienol, and uvaol have been isolated from it. β- and α-Amyrins, 24-ethylcholest-7-en-3β-ol and erythrodiol have also been identified in it by chromato-mass spectrometry.     

Highly Efficient Semiconductor Emitter of Single Photons in the Red Spectral Range

JETP Letters - The statistics of photon correlations in the emission of single InAs/AlGaAs quantum dots grown by molecular beam epitaxy and fitted with AlGaAs waveguide nanoantennas for efficient...     

Formation of SiC Mesastructures with Gently Sloping Sidewalls by Dry Selective Etching through a Photoresist Mask

Technical Physics - We have demonstrated that SiC mesastructures with gently sloping sidewalls form with the help of selective reactive ion etching (RIE) of silicon carbide through a photoresist...     

Lasing in microdisks with an active region based on lattice-matched InP/AlInAs nanostructures

The emissivity of unstrained quantum-dimensional InP/AlInAs nanostructures and their lasing properties in microdisk cavities prepared by wet etching have been studied. For as-prepared structures, it has been found that they radiate owing to quantum-dimensional InP islands 50–300 nm in diameter. At temperatures below 160 K, whispering gallery modes have been observed in the microdisks. Experimental data on the PL intensity for microcavity modes versus the pump power, which were obtained at liquid helium temperature, have made it possible to find the lasing threshold, 50 W/cm². The half-width of the laser line at above-threshold powers equals 0.06 nm, which corresponds to a Q factor of 15 000.     

Growth specifics of GaAs nanowires in mesa

The possibility of epitaxial growth of nanowire arrays on tilted faces of linear mesa has been demonstrated. The structural properties of GaAs nanowires grown on ( $33\bar 1$ ), ( $11\bar 7$ ), and (113) faces of samples with the (100) crystallographic orientation of the substrate have been studied. It has been found that there is a relation between the structural parameters of nanowires and the geometric orientation of the growth surface relative to the 〈111〉 directions and the surface of the substrate.     

Growth of thick AlN epilayers with droplet-free and atomically smooth surface by plasma-assisted molecular beam epitaxy using laser reflectometry monitoring

Low-temperature (<750 °C) growth of thick AlN epilayers on c-sapphire by plasma-assisted molecular-beam epitaxy under the Al-rich conditions (F_Al/F_N?<1.4) is reported here. Short periodic Al-flux interruptions controlled precisely by laser reflectometry ensure continuous growth of droplet-free and atomically smooth AlN films (rms<2 ML over 4 μm²) with a growth rate governed by the activated nitrogen flux. Lateral spreading of small accumulated Al clusters with their subsequent incorporation into the AlN layer during the Al-flux interruptions is supposed to be facilitated by activated nitrogen radicals. Strong influence of the remaining Al droplets on the subsequent growth of AlGaN/AlN superlattices is also demonstrated.