Papers by ALEXANDER PETROV
Poly (ethylene oxide) (PEO)/Polyvinyl pyrrolidone (PVP) blended solid polymer electrolytes comple... more Poly (ethylene oxide) (PEO)/Polyvinyl pyrrolidone (PVP) blended solid polymer electrolytes complexed with NaIO 4 salt at different weight percentage ratios were prepared using solution casting technique. Effect of salt complexation on structural properties of pure blend (PEO/PVP) electrolyte was investigated by X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopic (SEM) studies. Modifications in glass transition temperature and thermal stability of the blend electrolytes were measured by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) studies. The determined refractive index values from optical absorption spectra were found to increase with the increase of salt concentration. Impedance measurements were made in the frequency range of 0.1 Hz e1 MHz to explore dielectric response and ion dynamics of the blend electrolytes as a function of NaIO 4 salt concentration. The PEO/PVP blend complexed with 10 wt% of NaIO 4 salt was demonstrated higher room temperature conductivity of 1.56 Â 10 À7 S/cm. The temperature dependence of DC conductivity of blend electrolytes was followed the Arrhenius behaviour. Determined diffusion coefficients (D Naþ) using Trukhan model and estimated mobility (m) values of sodium ions were increased with increase of salt concentration. To get the further insights into the ion dynamics, the complex dielectric permittivity has been modeled with HavriliakeNegami function.
We studied three-component nanocomposite produced from nano-filled nematic by doping with photoac... more We studied three-component nanocomposite produced from nano-filled nematic by doping with photoactive azobenzene liquid crystal 4-(4'-ethoxyphenylazo)phenyl hexanoate (EPH) at concentration of 3 wt.%. The photo-insensitive host nanocomposite material (the filled nematic) was a gel formed from the nematic 4-n-heptyl cyanobiphenyl (7CB) and 3 wt.% of silica nanospheres (hydrophilic Aerosil 300) of size ca. 7 nm. The electrochemical impedance spectroscopy was applied to determine the UV-light-produced effect in EPH-doped aerosil/7CB upon continuous trans-to-cis photoisomerization of EPH molecules by varying the UV light intensity. The effect from UV illumination on the dielectric permittivity function of the studied photoresponsive nematic nanocomposite was analyzed at a room temperature in the frequency range 0.5 Hz – 200 kHz.
Thin films (25 µm) of nanocomposites formed from nematic liquid crystal (LC) pentylcyano-biphenyl... more Thin films (25 µm) of nanocomposites formed from nematic liquid crystal (LC) pentylcyano-biphenyl (5CB) doped with 0.5% wt. silver (Ag) nanospheres with a mean diameter ~ 10 nm were characterized by electrical measurements and dielectric spectroscopy in the frequency range from 1 mHz to 100 kHz. By using LC cells in which the electrodes are stripes of 1.2 mm width separated by a distance of 50 µm, it was possible to study the properties of Ag-5CB nematic nanocomposites by applying the external electric field either in the plane or perpendicular to the plane of the films. The results were compared with those obtained for undoped nematic 5CB in identical configurations of the experiments.
Flexoelectricity and Mechanotransduction
Current Topics in Membranes, 2007
The Lyotropic State of Matter: Molecular Physics and Living Matter Physics
Physics Today, 2000
Page 1. The Lyotropic State of Matter Molecular Physics and Living Matter Physics Alexander G. Pe... more Page 1. The Lyotropic State of Matter Molecular Physics and Living Matter Physics Alexander G. Petrov \ ' i °.J§ .-. . Gordon and Breach Science Publishers Page 2. Page 3. The Lyotropic State of Matter This One 1GTN-UU8-GJX1 Page 4. Page 5. ...
Photodissociation spectroscopy of the dysprosium monochloride molecular ion
The Journal of chemical physics, Jan 28, 2015
We have performed a combined experimental and theoretical study of the photodissociation cross se... more We have performed a combined experimental and theoretical study of the photodissociation cross section of the molecular ion DyCl(+). The photodissociation cross section for the photon energy range 35 500 cm(-1) to 47 500 cm(-1) is measured using an integrated ion trap and time-of-flight mass spectrometer; we observe a broad, asymmetric profile that is peaked near 43 000 cm(-1). The theoretical cross section is determined from electronic potentials and transition dipole moments calculated using the relativistic configuration-interaction valence-bond and coupled-cluster methods. The electronic structure of DyCl(+) is extremely complex due to the presence of multiple open electronic shells, including the 4f(10) configuration. The molecule has nine attractive potentials with ionically bonded electrons and 99 repulsive potentials dissociating to a ground state Dy(+) ion and Cl atom. We explain the lack of symmetry in the cross section as due to multiple contributions from one-electron-do...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2002
The High Acceptance Di-Electron Spectrometer (HADES) is a detector arrangement combined with a su... more The High Acceptance Di-Electron Spectrometer (HADES) is a detector arrangement combined with a superconducting toroid for lepton pair spectroscopy presently built up at GSI (Darmstadt). HADES is designed to cope with the high-multiplicity environment of heavy ion collisions at 1 AGeV and intensities of up to 10 8 beam particles per second and central event rates of 10 5 s À1 : The detector has a geometrical acceptance of almost 50% for e þ e À pairs and a mass resolution of 0.8% for r and o mesons. Four low-mass drift chamber systems, two before and two behind the magnet, serve for charged particle track reconstruction. Design aspects of the drift chambers and first results from beam tests are presented. r
The effect of external mechanical stress on the fullerite conductivity
Proceedings. 3rd Annual Siberian Russian Workshop on Electron Devices and Materials, 2002
The possibility to use powder consisting of fullerite microcrystals as device sensitive in extern... more The possibility to use powder consisting of fullerite microcrystals as device sensitive in external mechanical load is considered. As we suppose the change of conductivity of fullerite microcrystal powder as function of environmental mechanical stress is useful for creation of nanoscale devices of sensor electronics. This new effect based on changing of intermolecular distance between fullerene molecules due to action
Characterization of “TEMPOS”: A new Tunable Electronic Material with Pores in Oxide on Silicon
MRS Proceedings, 2003
Recently etched heavy ion tracks in MOS devices were filled with (semi)conducting materials to en... more Recently etched heavy ion tracks in MOS devices were filled with (semi)conducting materials to enable charge extraction from, or injection into the conducting channel below the Si/oxide interface, respectively. This leads to a family of novel electronic devices that we denoted ...
The conduction mechanisms of Cu and Ni nanotubules at their different formation stages
ABSTRACT
Pressure dependence of conductivity of fullerite structures
Catalysis Communications, 2003
It was shown earlier [A.S. Berdinsky et al., 2000] that the conductivity of fullerite depends on ... more It was shown earlier [A.S. Berdinsky et al., 2000] that the conductivity of fullerite depends on the applied pressure. In this paper we compare the pressure dependences of three different fullerite structures. On the one hand, we examined C/sub 60/ powder, filled into thin glass capillaries. On the other hand, we studied fullerite nanotubules produced within etched swift heavy ion
Dynamics of reactive ultracold alkali polar molecules
ABSTRACT
Hyperbolic blackbody
The blackbody theory is revisited in the case of thermal electromagnetic fields inside uniaxial a... more The blackbody theory is revisited in the case of thermal electromagnetic fields inside uniaxial anisotropic media in thermal equilibrium with a heat bath. When these media are hyperbolic, we show that the spectral energy density of these fields radically differs from that predicted by Planck's blackbody theory. We demonstrate that the maximum of their spectral energy density is shifted towards frequencies smaller than Wien's frequency making these media apparently colder. Finally, we derive Stefan-Boltzmann's law for hyperbolic media which becomes a quadratic function of the heat bath temperature.
Journal of the European Ceramic Society, 2015
The applications and processing of nanostructured materials at high temperatures require stabilit... more The applications and processing of nanostructured materials at high temperatures require stability of their morphology. However, in such environments (>1000 • C), these structures are prone to significant undesired microstructural changes that result in a loss of functional properties. The thermal stability of titania inverse opal films, prepared from self-assembled templates of monodisperse polystyrene spheres by infiltration utilizing atomic layer deposition and subsequent calcination, was assessed. Resistance to grain growth and a shift in the anatase-to-rutile transformation to higher temperatures was observed, with dramatic stability under vacuum. Vacuum annealed samples retained the anatase phase and exhibited minimal grain growth even after 3 h at 1300 • C. Photonic properties were retained until the transformation onset. The remarkable resistance was attributed to inhibition of surface diffusion and structure-substrate constraints. In addition to being technologically enabling, the results provide further insight into the titania system and its phase transformation mechanism.
2009 6th IEEE International Conference on Group IV Photonics, 2009
The maximum total gain in slow-light silicon Raman amplifiers is obtained when arranging for the ... more The maximum total gain in slow-light silicon Raman amplifiers is obtained when arranging for the largest-possible Stokes slow-down factor and a pump-power-dependent optimal pump slow-down factor.
Uploads
Papers by ALEXANDER PETROV