Resonance Behavior of the Forced Dissipative Spring-Pendulum System

Dynamics of the dissipative spring-pendulum system under periodic external excitation in the vicinity of external resonance and simultaneous external and internal resonances is studied. Analysis of the system resonance behaviour is made on the base of the concept of nonlinear normal vibration modes (NNMs), which is generalized for systems with small dissipation. The multiple scales method and subsequent transformation to the reduced system with respect to the system energy, an arctangent of the amplitudes ratio and a difference of phases of required solutions are applied. Equilibrium positions of the reduced system correspond to nonlinear normal modes. So-called Transient nonlinear normal modes (TNNMs), which exist only for some certain levels of the system energy are selected. In the vicinity of values of time, corresponding to these energy levels, these TNNMs temporarily attract other system motions. Interaction of nonlinear vibration modes under resonance conditions is also analysed. Reliability of obtained analytical results is confirmed by numerical and numerical-analytical simulation

Low background detector with enriched 116CdWO4 crystal scintillators to search for double beta decay of 116Cd

A cadmium tungstate crystal boule enriched in $^{116}$Cd to 82% with mass of 1868 g was grown by the low-thermal-gradient Czochralski technique. The isotopic composition of cadmium and the trace contamination of the crystal were estimated by High Resolution Inductively Coupled Plasma Mass-Spectrometry. The crystal scintillators produced from the boule were subjected to characterization that included measurements of transmittance and energy resolution. A low background scintillation detector with two $^{116}$CdWO$_4$ crystal scintillators (586 g and 589 g) was developed. The detector was running over 1727 h deep underground at the Gran Sasso National Laboratories of the INFN (Italy), which allowed to estimate the radioactive contamination of the enriched crystal scintillators. The radiopurity of a third $^{116}$CdWO$_4$ sample (326 g) was tested with the help of ultra-low background high purity germanium $\gamma$ detector. Monte Carlo simulations of double $\beta$ processes in $^{116}$Cd were used to estimate the sensitivity of an experiment to search for double $\beta$ decay of $^{116}$Cd.Comment: 24 pages, 13 figures, 3 tables, accepted for publication on Journal of Instrumentatio

Indium–tin oxide films obtained by extraction pyrolysis

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Thin indium–tin oxide (ITO) films were obtained by pyrolysis of solutions of indium and tin extracts on glass substrates. The extraction pyrolysis (EP) technology uses inexpensive starting compounds and provides the required stoichiometric ratio of elements due to complete mixing of precursors in the organic solution. The thermal decomposition of the extracts occurs in a narrow temperature range of 350– 400°C. X Ray photoelectron spectroscopy (XPS) studies showed that the ITO films obtained by extraction pyrolysis have no impurities including carbon. The films have a nanocrystalline structure with a grain size of ~6 nm according to XRD, AFM, and TEM studies. The optical transmission spectra showed that the films were highly transparent in the visible region of the spectrum and absorbed IR radiation at long and medium wavelengths

Structural Properties and State of a Zirconium Dioxide Surface Layer Modified with Mе3+ Cations

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The effect Ме3+ (Al, Y, Sc, Fe, and Mn) cations on the structural properties and state of a zirconium dioxide surface layer is investigated. The thermal stability of the Ме3+ solid solutions based on a metastable zirconium dioxide modification is established via X-ray diffraction analysis. It is shown using X-ray photoelectron spectroscopy that the distribution of surface–volume cationic modifier is determined by the type of cation. In Al-, Fe-, and Mn-ZrO2 systems, modifiers are mainly distributed over a surface; in Y and Sc-ZrО2, modifiers are distributed uniformly. The nature of the cation distribution affects the thermal stability of the solid solutions formed

Indium–tin oxide films obtained by extraction pyrolysis

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Thin indium–tin oxide (ITO) films were obtained by pyrolysis of solutions of indium and tin extracts on glass substrates. The extraction pyrolysis (EP) technology uses inexpensive starting compounds and provides the required stoichiometric ratio of elements due to complete mixing of precursors in the organic solution. The thermal decomposition of the extracts occurs in a narrow temperature range of 350– 400°C. X Ray photoelectron spectroscopy (XPS) studies showed that the ITO films obtained by extraction pyrolysis have no impurities including carbon. The films have a nanocrystalline structure with a grain size of ~6 nm according to XRD, AFM, and TEM studies. The optical transmission spectra showed that the films were highly transparent in the visible region of the spectrum and absorbed IR radiation at long and medium wavelengths

Fluorinated Surface of Carbon Nanotube Buckypaper for Uniform Growth of CdS Nanoparticles

Interfacial interactions between CdS species and multiwalled carbon nanotubes (MWCNTs) determine the architecture and optical characteristics of CdS/MWCNT hybrids. The effect of fluorinated surface of MWCNT buckypaper on the decoration with CdS nanoparticles from an ammonia solution of cadmium(II) chloride and thiourea has been studied. Scanning electron microscopy showed that the fluorinated carbon surface provides more dense growth and uniform distribution of CdS nanoparticles. X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopies revealed a partial defluorination of the nanotubes and the formation of elemental sulfur as a result of a joint action of thiourea and ammonia. The carbon atoms freed of fluorine were found from density functional theory calculations to be active sites for attachment of Cd(II) complexes present in the chemical bath and subsequent growth of CdS nanoparticles. The obtained hybrid possesses dual photoluminescence from fluorinated MWCNTs and CdS nanoparticles. Under applied electric field, it emits blue light that is possible only for very small CdS nanocrystals. This work provides a concept for fabrication of CNT-based hybrid structures with the high density of semiconducting nanoparticles for optoelectronic applications

On the nature of citrate-derived surface species on Ag nanoparticles: insights from X-ray photoelectron spectroscopy

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Citrate is an important stabilizing, reducing, and complexing reagent in the wet chemical synthesis of nanoparticles of silver and other metals, however, the exact nature of adsorbates, and its mechanism of action are still uncertain. Here, we applied X-ray photoelectron spectroscopy, soft X-ray absorption nearedge spectroscopy, and other techniques in order to determine the surface composition and to specify the citrate-related species at Ag nanoparticles immobilized from the dense hydrosol prepared using roomtemperature reduction of aqueous Ag+ ions with ferrous ions and citrate as stabilizer (Carey Lea method). It was found that, contrary to the common view, the species adsorbed on the Ag nanoparticles are, in large part, products of citrate decomposition comprising an alcohol group and one or two carboxylate bound to the surface Ag, and minor unbound carboxylate group; these may also be mixtures of citrate with lower molecular weight anions. No ketone groups were specified, and very minor surface Ag(I) and Fe (mainly, ferric oxyhydroxides) species were detected. Moreover, the adsorbates were different at AgNPs having various size and shape. The relation between the capping and the particle growth, colloidal stability of the high-concentration sol and properties of AgNPs is briefly considered