Pulsed-laser fabrication of noble-metal nanorings with a tunable internal porous structure, which can be further uncapped by using an ion-beam etching procedure, was demonstrated for the first time. Density and averag...
Pulsed-laser fabrication of noble-metal nanorings with a tunable internal porous structure, which can be further uncapped by using an ion-beam etching procedure, was demonstrated for the first time. Density and average size of the pores were shown to be tuned in a wide range by varying an applied pulse energy and a chemical composition of the metal film controlled via the film magnetron deposition in the appropriate gaseous environment. According to our preliminary numerical simulations, the controlled porosity provides multifold near-field enhancement of the electromagnetic fields, making such structures promising for spectroscopic bioidentification based on a surface-enhanced Raman scattering.
Two-layer heterostructure with GaSb nanocrystals formed by solid phase epitaxy and embedded into the silicon was investigated using low-temperature (10-140 K) photoluminescence and time-resolved photoluminescence spec...
Two-layer heterostructure with GaSb nanocrystals formed by solid phase epitaxy and embedded into the silicon was investigated using low-temperature (10-140 K) photoluminescence and time-resolved photoluminescence spectroscopies. Two characteristic luminescence bands with a maximum of about 0.82 and 0.87 eV were observed. It was found that low-energy peak is associated with D1 dislocation-related luminescence in silicon. Analysis of the decay components together with temperature and power dependencies of the photoluminescence for the high-energy maximum revealed that emission is more likely originated from the combined D2 dislocation centers in silicon and radiative recombination in type–II band alignment Si/GaSb nanocrystals/Si heterostructure. A nonradiative recombination dominates in all temperature range studied.
The gas flows in the gravity field through porous objects with heat-releasing sources are investigated when the self-regulation of the flow rate of the gas passing through the porous object takes place. Such objects c...
The gas flows in the gravity field through porous objects with heat-releasing sources are investigated when the self-regulation of the flow rate of the gas passing through the porous object takes place. Such objects can appear after various natural or man-made disasters (like the exploded unit of the Chernobyl NPP). The mathematical model and the original numerical method, based on a combination of explicit and implicit finite difference schemes, are developed for investigating the time-dependent processes in 3D porous energy-releasing objects. The advantage of the numerical model is its ability to describe unsteady processes under both natural convection and forced filtration. The gas cooling of 3D porous objects with different distribution of heat sources is studied using computational experiment.
Embedded in silicon β-FeSi2 nanocrystals (NCs) were grown on Si(111) by solid phase epitaxy of a thin iron film followed by Si molecular beam epitaxy. After solid phase epitaxy, a mixture of β-FeSi2 and ε-FeSi nano...
Embedded in silicon β-FeSi2 nanocrystals (NCs) were grown on Si(111) by solid phase epitaxy of a thin iron film followed by Si molecular beam epitaxy. After solid phase epitaxy, a mixture of β-FeSi2 and ε-FeSi nanocrystals is formed on the surface, sometimes β and ε phases coexist inside one nanocrystal. During initial stage of Si molecular beam epitaxy all ε-FeSi transforms into β-FeSi2. β-FeSi2 nanocrystals tend to move following Si growth front. By adjusting growth condition, we manage to prevent the nanocrystals from moving and to fabricate 7-layer n-Si(111)/β-FeSi2_NCs/p+-Si silicon heterostructure with embedded β-FeSi2 NCs. An epitaxial relationship and a stress induced in the nanocrystals by silicon matrix were found to be suitable for indirect to direct band gap transition in β-FeSi2. Of the heterostructure, a n-i-p avalanche photodetector and a light-emitting diode were formed. They have shown relatively good performance: ultrabroadband photoresponse from the visible (400 nm) to short-wavelength infrared (1800 nm) ranges owing to quantum-confined Stark effect in the nanocrystals and optical emission power of up to 25 µW at 9 A/cm2 with an external quantum efficiency of 0.009% at room temperature owing to a direct fundamental transition in stressed β-FeSi2 nanocrystals.
In this report we present the experimental study of imaging photoplethysmography in the area of the palm and wrist of fifty-six healthy subjects. We found that the amplitude of the PPG waveform is unevenly distributed...
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In this report we present the experimental study of imaging photoplethysmography in the area of the palm and wrist of fifty-six healthy subjects. We found that the amplitude of the PPG waveform is unevenly distributed over the studied area forming the hot spots with the elevated amplitude. There is clear tendency of the amplitude increasing in the hottest spots with the age of the subject. These observations support the recently proposed model of photoplethysmography in which pulse oscillations of the arterial transmural pressure deform the connective-tissue components of the dermis resulting in periodical changes of both the light scattering and absorption.
The paper presents a reflectometric technique for interrogation of multiple fiber Bragg grating (FBG) sensors based on conventional optical time domain reflectometry (OTDR). The method proposed rests on the differenti...
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To study structural and transport properties of the surface phases on silicon, a number of adsorbate/silicon systems on Si(100) and Si(111) surfaces has been investigated using scanning tunneling microscopy (STM), ref...
To study structural and transport properties of the surface phases on silicon, a number of adsorbate/silicon systems on Si(100) and Si(111) surfaces has been investigated using scanning tunneling microscopy (STM), reflection-high-energy-electron diffraction (RHEED) and in-situ electrical resistance measurements. Results of investigations of formation and electrical properties of Si-Al, Si-Na, Si-Ag and Si-In surface structure are presented.
The results of the experiments on femtosecond GW laser pulse interaction with isolated millimeter-sized water droplets are presented Temporal and spatial dynamics of optical breakdown in a liquid particle volume is in...
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The results of the experiments on femtosecond GW laser pulse interaction with isolated millimeter-sized water droplets are presented Temporal and spatial dynamics of optical breakdown in a liquid particle volume is investigated. The mechanical fragmentation of the droplet as a result of the evaporation and explosion of superheated areas is also discussed. The spectral characteristics of water particle emission during its explosive boiling are investigated.
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