Nanoparticles of nonstoichiometric magnetite obtained by controlled oxidation of carbonyl iron (α-Fe) in water are studied. The Fe : H
2
O mole ratio is 3 : 4, 4 : 4 and 3 : 10. The particles are ...synthesized in a high-power Activator 2S mill in an air atmosphere by 24-h milling. X-ray diffraction and spectrum analyses of the synthesized magnetite nanoparticles are performed. Formulas describing the crystal chemistry of the nanoparticles are derived using the data of Mossbauer spectroscopy. The magnetic properties and the microstructure of the nanoparticles are studied.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Multi-filamentation of high power femtosecond laser pulses in water.•Fabrication of sub-diffraction surface ripples on wet aluminum by high optical harmonics.
Relief ripples with sub-diffraction ...periods (≈λlas/3, λlas/4) were produced on a aluminum surface immersed in water and irradiated in a multi-filamentation regime by focused 744nm femtosecond laser pulses with highly supercritical, multi-GW peak powers. For the VUV (8.5eV) surface plasmon resonance on the wet aluminum surface, such small-scale surface nanogratings can be produced by high – second and third – optical harmonics, coming to the surface from the optical filaments in the water layer. Then, the sub-diffraction surface ripples may appear through interference of their transverse electric fields with the longitudinal electric fields of their counterparts, scattered on the surface roughness and appeared as the corresponding high-energy, high-wavenumber surface polaritons.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The possibility of using river seismic data for oil and gas exploration to study the deep structure of the Earth’s crust is shown. This method uses water seismic source points and bank-mounted ...autonomous seismic recorders installed for continuous seismic recording. About 2700 km of seismic profiles were completed by the CDP-2D method along the rivers of Eastern Siberia (Lena, Nizhnyaya Tunguska, and Vitim). The structure of the upper part of the Earth’s crust (up to several kilometers) has been studied, while its deep structure remains unknown. It is shown that the materials of seismic river surveys carried out along a 60-km section of the profile in the lower reaches of the Lena River, using the method developed by the Geophysical Survey, Russian Academy of Sciences, contain data allowing us to construct cross sections throughout the thickness of the Earth’s crust up to the Moho boundary. Low-amplitude fluctuations of reflected waves from deep boundaries are distinguished due to the wide dynamic range of the devices used and the multiple summation, which is significantly higher than in the case of the traditional seismic surveys. The high multiplicity is achieved by reducing the distance between blast points, increasing the sounding bases and the binning area.
This paper reports the results of satellite image and seismological data analysis obtained when considering the causes of a landslide on the Yelbashinskii dump at the Kolyvan anthracite deposit. The ...potential for determining the natural vibrations of large objects from low-frequency seismological records and monitoring thereof has been demonstrated.
The paper describes the thermodynamic modeling and experimental study of the synthesis of vanadium oxide films at various temperatures from the tetrakis(ethylmethylaminovanadium) VNC
3
H
8
4
...precursor in the presence of oxygen in an argon atmosphere. The thermodynamic modeling was carried out using the calculation of chemical equilibria based on the minimization of the Gibbs energy of the system. In the experimental part of the paper, the films were synthesized by the atomic layer deposition procedure. The thermodynamic modeling and experimental results agree with each other and can be used to develop procedures for the synthesis of film coatings based on vanadium oxides.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This article presents the results of deep seismic studies over the Sikhote-Alin fragment of the 8-DV reference geophysical profile running across the large fold structures of the Pacific tectonic ...belt, that is, the Sikhote-Alin Orogenic Belt with the superimposed Middle Amur sedimentary basin and the East Sikhote-Alin volcanoplutonic belt. A deep seismic section of the Earth’s crust and upper mantle with the distribution of longitudinal wave velocities is constructed. In the upper part of the section, P-wave velocities vary from 4.0–5.0 km/s within the Middle Amur sedimentary basin and the eastern part of the Eastern Sikhote-Alin volcanoplutonic belt to 5.5–5.6 km/s in the central part of the Sikhote-Alin Orogenic Belt. It was established that the thick Paleozoic sedimentary complex within the Middle Amur sedimentary basin is faulted and folded in a complex manner. Crystalline rocks with a compressional wave velocity of 6.0–6.2 km/s occur at depths from 8 to13 km in different parts of the Middle Amur sedimentary basin and at depths of 4–6 km within the Sikhote-Alin orogenic complex. Compressional wave velocities of the crust in the Sikhote-Alin fragment of the 8-DV profile are between 6.3 and 6.35 km/s. The crust varies in thickness from 32–34 km in the northern part of the fragment to 36–37 km in its central and eastern parts. Along the Moho, P-wave velocities are 8.1–8.3 km/s; a number of areas with reduced
V
p
of 7.8 to 8.0 km/s were identified in the junction zones of large crustal blocks.
P
-wave data were used to identify anomalies which were correlated with structural-tectonic zones, deep fault zones, and seismicity. The thick Middle Amur sedimentary basin was distinguished along the Central Sikhote-Alin deep fault. This basin is filled by Paleozoic low-velocity deposits and is displaced along the fault plane by 4–5 km at its junction with the Sikhote-Alin Orogenic Belt. Zones of increased heterogeneity in the upper crust projected onto the area within the contours of the Middle Amur sedimentary basin are characterized by increased seismicity.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Nanostructured near-IR antireflective layer was produced on a GaAs slab surface by direct femtosecond laser fabrication of a surface diffraction grating. The single nanostructured layer on the GaAs ...slab reduces its total reflection at the wavelength λ ≈ 2.5 μm by 42 %, in agreement with the second-order approximation of the effective medium theory, with negligible increase of its absorbance.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Thin aluminum film homogeneously heated by intense IR femtosecond laser pulses exhibits on the excitation timescale consequent fluence-dependent rise and drop of the IR-pump self-reflectivity, ...followed by its final saturation at higher fluences
F
> 0.3 J/cm
2
. This prompt optical dynamics correlates with the initial monotonic increase in the accompanying laser-induced electron emission, which is succeeded by its non-linear (three-photon) increase for
F
> 0.3 J/cm
2
. The underlying electronic dynamics is related to the initial saturation of IR resonant interband transitions in this material, followed by its strong instantaneous electronic heating via intraband transitions during the pump pulse resulting in thermionic emission. Above the threshold fluence of 0.3 J/cm
2
, the surface electronic heating is balanced during the pump pulse by simultaneous cooling via intense plasma removal (prompt ablation). The relationship between the deposited volume energy density in the film and its prompt electronic temperature derived from the self-reflection measurements using a Drude model, demonstrates a kind of electron “liquid–vapor” phase transition, driven by strong cubic optical non-linearity of the photo-excited aluminum.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•In a scanning regime, a symmetrical fs-laser beam yields in nanostructured microspikes.•Smooth and less oxidized microspikes were obtained using an asymmetrical fs-laser beam.•Surface topology and ...oxidation degree depends on scanning direction in the asymmetrical case
We have developed a new method for manipulating nanotopology and chemical composition of titanium surfaces by a scanning femtosecond laser beam with an asymmetrical spatial fluence distribution. Using of a common Gaussian laser beam leads to formation of combined nano- and micro-scale surface topologies owing to superimposition of different laser beam parts during the surface scanning. In contrast, beam shaping results in presumable surface structuring at specific laser fluences yielding in “clean” surface structures. In a simple case, cutting of a half beam perpendicular to the scanning direction enables to eliminate surface nanotopology, leaving less oxidized, cleaner and smoother microspikes, just by changing the scanning direction. Optimal experimental conditions were revealed to obtain in air the topologically and chemically different surface structures using the asymmetrical femtosecond laser beam and the opposite scanning directions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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