3,016 research outputs found
Author Correction: Casimir forces exerted by epsilon-near-zero hyperbolic materials (Scientific Reports, (2020), 10, 1, (16831), 10.1038/s41598-020-73995-0)
No full textIn the original version of this Article, Igor S. Nefedov was incorrectly affiliated with “Saratov State University, Astrakhanskaya 83, Saratov, Russian Federation, 410012”. The correct affiliation is listed below: Peoples’ Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya St., Moscow 117198, Russia. This error has now been corrected in the HTML and PDF versions of the Article. © 2020, The Author(s)
PKE–Nefedov*: plasma crystal experiments on the International Space Station
No full textAbstract. The plasma crystal experiment PKE–Nefedov, the first basic science experiment on the International Space Station (ISS), was installed in February 2001 by the first permanent crew. It is designed for long-term investigations of complex plasmas under microgravity conditions. ‘Complex plasmas ’ contain ions, electrons, neutrals and small solid particles—normally in the micrometre range. These microparticles obtain thousands of elementary charges and interact with each other via a ‘screened ’ Coulomb potential. Complex plasmas are of special interest, because they can form liquid and crystalline states (Thoma
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PKE-Nefedov*: Plasma crystal experiments on the International Space Station
No full textThe plasma crystal experiment PKE-Nefedov, the first basic science experiment on the International Space Station (ISS), was installed in February 2001 by the first permanent crew. It is designed for long-term investigations of complex plasmas under microgravity conditions. 'Complex plasmas' contain ions, electrons, neutrals and small solid particles - normally in the micrometre range. These microparticles obtain thousands of elementary charges and interact with each other via a 'screened' Coulomb potential. Complex plasmas are of special interest, because they can form liquid and crystalline states (Thomas et al 1994 Phys. Rev. Lett. 73 652-5, Chu and I 1994 Phys. Rev. Lett. 72 4009-12) and are observable at the kinetic level. In experiments on Earth the microparticles are usually suspended against gravity in strong electric fields. This creates asymmetries, stresses and pseudo-equilibrium states with sufficient free energy to readily become unstable. Under microgravity conditions the microparticles move into the bulk of the plasma (Morfill et al 1999 Phys. Rev. Lett. 83 1598), experiencing much weaker volume forces than on Earth. This allows investigations of the thermodynamics of strongly coupled plasma states under substantially stress-free conditions. In this first paper we report our results on plasma crystals, in particular the first experimental observations of bcc lattice structures
Real time investigation of the initial stages of a-C films growth
No full texta-C films were deposited by rf-PACVD. Their growth rate, thickness, density and roughness were derived during deposition from time dependent X-ray reflectivity (XRR) at a wavelength of 1.54 A and at a fixed incidence angle of 18. It is shown that the film density and surface roughness are not constant at the initial stages of growth. The density increases with increasing film thickness, while the surface roughness depends on the substrate roughness. The evolution of these parameters was measured also while etching the film in oxygen plasma and revealed the smoothing effect brought about by etching to the carbon surfac
A study of capacitance-voltage characteristics of amorphous carbon multilayer nanostructures
No full textDark and illuminated capacitance–voltage (C–V) characteristics and admittance measurements were carried out on multilayer carbon structures.The latter were produced by depositing ultrathin amorphous carbon layers with different optical band gaps on a monocrystalline boron-doped silicon substrate.The carbon layers were grown either by magnetron sputtering (MS) of a graphite target in argon or by plasma ion beam deposition (IBD) in cyclohexane.The structures were characterised by X-ray reflectivity (XRR). With respect to their electrical properties, it was shown that light strongly affects both the C–V-characteristics and the admittance.The results were interpreted in terms of the energy levels in these amorphous carbon multilayer structure
X-ray reflectivity study of the early stages of a-C:H film growth
No full textThe initial stages of hydrogenated amorphous carbon films growth are investigated by in situ and ex situ X-ray reflectivity (XRR) at a wavelength of 1.54 Å. Hydrogenated amorphous carbon films were deposited by rf-plasma-assisted chemical vapor deposition. The results are considered in connection with the main models of film growth, namely, layer-by-layer or island (hemispherical, cylindrical) formation. It is shown that the film density increases at the initial stages of growth and different possible reasons for this are discusse
Iodine incorporation into polymeric films investigated by angle-resolved XPS
No full textDistribution of elements into subsurface layers (up to 120 angstrom thickness) of polyphenylacetylene (PPA) films doped with I2 vapour has been determined by X-ray photoelectron spectroscopy data using a unique numerical technique. Concentration of incorporated iodine has been shown to increase with exposure time; the concentration profiles are dome-shaped and iodine does not penetrate much into the bulk of PPA films, even when exposed to I2 vapours for 1 h. The depth of the layer corresponding to maximum iodine concentration is directly proportional to the iodine exposure time. The non-homogeneous distribution of the doping species in the polymer may be responsible for the low conductivity observed for heterogeneously doped PPA films
Observation of photodiode and electroluminescence effects for a-C/a-C:H multilayer nanostructures on silicon
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Formation and behaviour of dust particle clouds in a radio-frequency discharge: Results in the laboratory and under microgravity conditions
No full textIn this paper we report the first observation on submicron dust particle clouds grown in a radio-frequency sputtering discharge under microgravity conditions. These results have been obtained in the PKE-Nefedov (Plasma Kristall Experiment) chamber in the framework of a French-German-Russian programme. A dust-free region, usually called the 'void', is observed in the laboratory and under microgravity conditions even with submicron particles. In this region, successive generations of particles can be grown, leading to the coexistence of particles with various sizes. Each generation of particles constitutes a cloud separated from the others by a definite sheath. Dynamics of these clouds have been investigated showing vortex-like motions or independent behaviour of small heaps of particles, emphasizing both attractive and repulsive effects between dust clouds. As these particles drastically influence the plasma properties, the growth kinetics is followed through the evolution of the discharge current
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