Clustering in thin silver films upon heating

The kinetics of the formation of silver clusters Ag from nanoscale continuous films of Ag on the surface of silicate glass and composite structures from films of Ag with carbon in the form of a continuous film and individual nanoparticles upon annealing in air at temperatures up to 670K is investigated. In the course of the work, the dependences of the surface morphology of silver clusters and absorption spectra in the visible wavelength range were obtained by the methods of atomic force microscopy and optical spectrophotometry.

Energy Distribution of Optical Radiation Emitted by Electrical Discharges in Insulating Liquids

This article presents the results of the analysis of energy distribution of optical radiation emitted by electrical discharges in insulating liquids, such as synthetic ester, natural ester, and mineral oil. The measurements of optical radiation were carried out on a system of needle–needle type electrodes and on a system for surface discharges, which were immersed in brand new insulating liquids. Optical radiation was recorded using optical spectrophotometry method. On the basis of the obtained results, potential possibilities of using the analysis of the energy distribution of optical radiation as an additional descriptor for the recognition of individual sources of electric discharges were indicated. The results can also be used in the design of various types of detectors, as well as high-voltage diagnostic systems and arc protection systems.

Morphology and orientated growth of second-phase precipitates in a Eu2+-doped equimolar KCl:KBr solid solution: an epifluorescence microscopy study by using the doping ion as a fluorochrome

The shape and orientation of second-phase precipitates in a Eu2+-doped equimolar KCl:KBr solid solution are reported in this paper as they were unveiled by epifluorescence microscopy. To make this, microscopy images of different optical cross sections of some precipitate fields and, also, of some representative precipitates in these fields, were recorded by using the Eu2+ ion itself as a fluorochrome. From these images, the corresponding precipitate fields and individual precipitates were electronically reconstructed into the host lattice space. Previously, the KCl:KBr:Eu2+ system was characterized by absorption and fluorescence optical spectrophotometry, to tailor properly the fluorescence mirror unit, as well as by powder and single-plate X-ray diffraction, to correlate the host lattice orientation with those of the observed precipitates. These are shaped as plates, with broad faces parallel to host lattice {100}, {110} or {120}planes (the {100}, {110} and {120} precipitates, respectively), and as rods, aligned with a host lattice ˂100> direction (the ˂100> precipitates). The {100}, {110}, {120}-precipitate broad faces are in the shapes of 72.6° rhomboids, rectangles and 59.5° rhomboids, with a side lying along host lattice <310>, <110> and <421> directions, respectively, and with another side lying along a <100> direction. A typical precipitate field and the spatial reconstructions of typical {100}, {110}, {120} and ˂100> precipitates, as well as their corresponding electronic 3D-geometrical models, are described in detail. It is discussed that four different europium precipitation states are responsible for the precipitation and that the precipitate lattices are spatially coherent with the host lattice.

Radiation in the Optical and UHF Range Emitted by Partial Discharges

This paper presents the results of analysis of a solid dielectric’s influence on the phenomena associated with the signals emitted by surface partial discharges. Three types of electrode systems were tested, in which solid dielectrics made of pressboard, Teflon, and glass were used. The emission of such signals as radio waves in the Ultra high frequency (UHF) range and optical radiation was analyzed. The measurements were carried out in the insulation systems most commonly used in electrical power equipment, i.e., mineral oil and air. UHF and optical spectrophotometry methods were used to register the emitted signals. The obtained results indicate that the type of material from which the dielectric solid is made may have a potential impact on some ranges of emitted electromagnetic waves during the surface electrical discharges. The research topic undertaken is important in issues associated with high-voltage insulation systems and in particular with surface discharges, which are often the cause of their damage.

Application of Optical Spectrophotometry for Analysis of Radiation Spectrum Emitted by Electric Arc in the Air

This paper presents the results of measurement and analysis of optical radiation emitted by a free burning electric arc. The aim was to determine the application possibilities of optical spectrophotometry for detection of electric arcs. The research works considered electric arc generated with a constant voltage supply between two copper electrodes in the air, carried out under laboratory conditions. A high resolution optical spectrophotometer was used for registration of optical radiation. The analyses involved determination of two dimensionless descriptors obtained for the gathered spectra. Moreover, for each of the registered intensity distributions, the energy values were calculated for three frequency ranges. Based on the measured signals, the possibility of application of spectrophotometry for the optical radiation analysis was confirmed. The analysis indicated that the most energy of optical radiation is detected for the range of 200–780 nm, while above 780 nm almost no optical energy is emitted. Spectrophotometric studies performed in the UV-NIR range are of interest since one can obtain information about the structural defects (at lower wavebands) or impurities and/or point defects (at low energies bands). It was also stated that the obtained descriptors may be applied for diagnosis and identification of electric arc purposes.