Thermal expansion of a lead sulfide nanofilm

The thermal expansion of a lead sulfide nanofilm produced by chemical bath deposition was determined by X-ray diffraction (XRD). The thickness of the synthesized film was about 100 nm, and the average size of the coherent scattering regions as determined from XRD was about 40 nm. The lattice constant of the PbS nanofilm was measured as a function of the annealing temperature from 293 to 473 K and as a function of the annealing time at a constant temperature of 423 K. The thermal expansion coefficient derived was found almost twice as large as that for coarse-grained PbS. © 2013 Elsevier B.V. All rights reserved. All rights reserved

Hybrid nanoparticles based on sulfides, oxides, and carbides

The methods for synthesis of hybrid nanoparticles based on sulfides, oxides, and carbides of heavy and transition metals were considered. The problem of the influence of the method of synthesis of the hybrid nanoparticles on their atomic structure, morphology of the nanomaterials, and functional properties was analyzed. The areas of practical use of the hybrid nanoparticles were proposed. © 2013 Springer Science+Business Media New York

Magnetohydrodynamic Waves in Partially Ionized Prominence Plasmas

Prominences or filaments are cool clouds of partially ionized plasma living in the solar corona. Ground- and space-based observations have confirmed the presence of oscillatory motions in prominences and they have been interpreted in terms of magnetohydrodynamic (MHD) waves. Existing observational evidence points out that these oscillatory motions are damped in short spatial and temporal scales by some still not well known physical mechanism(s). Since prominences are partially ionized plasmas, a potential mechanism able to damp these oscillations could be ion-neutral collisions. Here, we will review the work done on the effects of partial ionization on MHD waves in prominence plasmas.Comment: Review paper to appear in Astrophysics and Space Science Proceeding

Local helioseismology of sunspot regions: comparison of ring-diagram and time-distance results

Local helioseismology provides unique information about the subsurface structure and dynamics of sunspots and active regions. However, because of complexity of sunspot regions local helioseismology diagnostics require careful analysis of systematic uncertainties and physical interpretation of the inversion results. We present new results of comparison of the ring-diagram analysis and time-distance helioseismology for active region NOAA 9787, for which a previous comparison showed significant differences in the subsurface sound-speed structure, and discuss systematic uncertainties of the measurements and inversions. Our results show that both the ring-diagram and time-distance techniques give qualitatively similar results, revealing a characteristic two-layer seismic sound-speed structure consistent with the results for other active regions. However, a quantitative comparison of the inversion results is not straightforward. It must take into account differences in the sensitivity, spatial resolution and the averaging kernels. In particular, because of the acoustic power suppression, the contribution of the sunspot seismic structure to the ring-diagram signal can be substantially reduced. We show that taking into account this effect reduces the difference in the depth of transition between the negative and positive sound-speed variations inferred by these methods. Further detailed analysis of the sensitivity, resolution and averaging properties of the local helioseismology methods is necessary for consolidation of the inversion results. It seems to be important that both methods indicate that the seismic structure of sunspots is rather deep and extends to at least 20 Mm below the surface, putting constraints on theoretical models of sunspots.Comment: 10 pages, 10 figures, submitted to Journal of Physics: Conference Series (JPCS) GONG 2010 - SoHO 24 "A new era of seismology of the Sun and solar-like stars", June 27 - July 2, 2010 Aix-en-Provence, Franc

Observation and Modeling of the Solar-Cycle Variation of the Meridional Flow

We present independent observations of the solar-cycle variation of flows near the solar surface and at a depth of about 60 Mm, in the latitude range $\pm45^\circ$. We show that the time-varying components of the meridional flow at these two depths have opposite sign, while the time-varying components of the zonal flow are in phase. This is in agreement with previous results. We then investigate whether the observations are consistent with a theoretical model of solar-cycle dependent meridional circulation based on a flux-transport dynamo combined with a geostrophic flow caused by increased radiative loss in the active region belt (the only existing quantitative model). We find that the model and the data are in qualitative agreement, although the amplitude of the solar-cycle variation of the meridional flow at 60 Mm is underestimated by the model.Comment: To be published in Solar Physcis Topical Issue "Helioseismology, Asteroseismology, and MHD Connections

Induced surface photovoltage in TiO2 sol-gel nanoparticles

TiO2 nanoparticles synthesized by the sol-gel method and modified by annealing in air and hydrogen atmospheres were studied by surface photovoltage spectroscopy (SPS). SPS measurements showed that the modified in air TiO2 nanoparticles have a more intense signal than those treated in hydrogen. A linear correlation was found between the SPS and the diffuse reflectance spectra of the samples. © Dorosheva I.B., Vokhmintsev A.S., Weinstein I.A., Rempel A.A., 2023.Ministry of Education and Science of the Russian Federation, Minobrnauka: FEUZ-2023-0014A.S.V. and I.A.W. thank the Ministry of Science and Higher Education of the Russian Federation (research project FEUZ-2023-0014) for support. Part of synthesis of titanium dioxide carried out within the framework of RF State assignment for IMET UB RAS.ABSTRACT TiO2 nanoparticles synthesized by the sol-gel method and modified by annealing in air and hydrogen atmospheres were studied by surface photovoltage spectroscopy (SPS). SPS measurements showed that the modified in air TiO2 nanoparticles have a more intense signal than those treated in hydrogen. A linear correlation was found between the SPS and the diffuse reflectance spectra of the samples. KEYWORDS Titanium dioxide, sol-gel method, nanoparticles, surface photovoltage (SPV). ACKNOWLEDGEMENTS A.S.V. and I.A.W. thank the Ministry of Science and Higher Education of the Russian Federation (research project FEUZ-2023-0014) for support. Part of synthesis of titanium dioxide carried out within the framework of RF State assignment for IMET UB RAS. FOR CITATION Dorosheva I.B., Vokhmintsev A.S., Weinstein I.A., Rempel A.A. Induced surface photovoltage in TiO2 sol-gel nanoparticles. Nanosystems: Phys. Chem. Math., 2023, 14 (4), 447–453

SELFORGANIZATION OF NANOPARTILCES IN THE SYSTEM OFSILVER SULFIDE-MERCAPTOPROPYLSILANE

In present work, a selforganization of 50 nm Ag2S nanoparticles stabilized with mercaptopropylsilane is discovered. The structure and chemical composition of microtubes grown upon the selforganization is determined by optical and electron microscopy, and by energy dispersive X-ray analysis

Solar dynamo

No abstract available