Technical Physics Letters最新文献

Abstract—The influence of irradiation with accelerated electrons (energy 8.5 MeV, dose 5 kGy) on the physical properties of medical devices made of polyethylene terephthalate (PET) was studied by infrared (IR) spectroscopy. The revealed post-irradiation changes in the IR spectra can be used to justify the choice of the dose of irradiation of PET products with electrons during the radiation sterilization procedure.

Abstract—We have considered the interaction of an exciton mode with photonic modes in a GaN structure several pm in size. A technique for obtaining spectra from such structures has been demonstrated. The cavity shape and dimensions most optimal for efficient light/matter interaction have been selected. The theoretical spectrum for the selected cavity has been obtained and analyzed.

Abstract—A new analytic theory is developed for asymptotic stage of self-catalyzed growth of III–V nanowires (NWs) by molecular beam epitaxy (MBE), where NWs collect all group III atoms deposited from vapor. The shadowing NW length is derived which corresponds for the full shadowing of the substrate surface in MBE. The NW length and radius are derived depending on the effective deposition thickness and MBE growth parameters. It is shown that the NW length increases, and their length decreases with decreasing the array pitch and increasing the V/III flux ratio.

Abstract—The study of the effect of the initial conditions on the features of the formation and development of the anodic ionization wave between two electrodes with a tip–plane gap geometry in argon at atmospheric pressure is performed on the basis of a two-dimensional axisymmetric drift-diffusion model.

The elastic interaction of quantum disks (QDs) in a nanowire (NW), i.e., in a hybrid QD/NW structure with sharp heterointerfaces, is considered for the first time. Within the framework of the defect micromechanics approach, the energy of QD pair interaction is established and it is demonstrated that for QDs with a lattice misfit of the same sign, a zone of attraction to each other appears, depending on the ratio of the QD axial size to the NW radius. The discovered effect should be taken into account when choosing the modes of formation of hybrid QD/NW structures and in models explaining their properties.

The effect of enhancement the hydrophobic properties of the ensemble of micro- and nanostructures ZnO as a result of coating with gold was discovered. For the first time, it has been shown that coating the ensemble with a micro- and nanoparticle ZnO layer of gold leads to a sharp increase in the wetting edge angle from 145° to 168° (water drop volume 5 mm³) and a decrease in the hydrophobicity/hydrophilicity transition time under ultraviolet irradiation.

The results of experimental studies evaluating the influence of longitudinal slits in a conical diffraction outlet, combined with an electron collector, of a 10 GHz relativistic BWO (Backward-Wave Oscillator) with an operating mode TM₀₁ are presented. It has been shown experimentally that replacing a solid conical waveguide with a similar longitudinal-slotted waveguide has little effect on the performance of the BWO. The use of a longitudinally slotted diffraction outlet instead of a continuous one makes it possible to reduce the volume of plasma and microparticles formed on the diffraction outlet surface under the action of an electron beam, and to improve their adsorption and removal.

Abstract—The analysis of supercavities formed during the high-speed motion in water of two closely spaced supercavitating strikers is performed. By comparing geometric characteristics of supercavities, the possibility of qualitative assessment of influence degree of closely spaced strikers on each other is shown. By the example of two strikers, the characteristic distance between them was determined, at which the minimum mutual influence of the strikers on each other is observed.

Abstract—The paper presents the results of mechanical properties scanning by means of nanoindentation across the annual growth rings of deciduous trees wood, small-leaved lime (Tilia cordata) and common oak (Quercus robur) in particular. Significant variations in microhardness H and Young’s modulus E radial dependencies have been found for any of the studied species. Results can be useful (1) to amend the understanding the nature of macromechanical properties of various wood species and to reveal the details of their formation depending upon microstructural characteristics, (2) to optimize the technologies of growing, reinforcement and subsequent usage of the wood, (3) to develop new independent methods in dendrochronology and dendroclimatology.

Abstract—The effect of secondary spontaneous boiling of submerged jets formed during the collapse of vapor bubbles during the bulk boiling of water subcooled to the saturation temperature at the end of a laser optical fiber is experimentally discovered.