Luminescence of poly(N-vinylcarbazole) in the solution and solid state

Fluorescence spectra of poly(N-vinylcarbazole) have been studied as a function of various environments and temperature. Fluorescence spectra have been excited with UV light from 200 W Xenon lamp or with second-harmonics of a pulsed ruby laser. Polymer films and powders show exclusively excimer fluorescence at room temperature. At high intensities of excitation the observed fluorescence spectra have a weak quasiperiodic structure.     

Polar state in a SrTiO3-KTaO3 solid solution

Dielectric properties of ceramic samples of a 0.85SrTiO₃-0.15KTaO₃ solid solution have been studied. The temperature dependence of the dielectric permittivity exhibits maxima with a strong frequency dispersion, which is described by the Vogel-Fulcher law with a characteristic temperature T _g=26 K. These features are apparently connected with transition to a polar glasslike state. Fiz. Tverd. Tela (St. Petersburg) 39, 1838–1840 (October 1997)     

Structural state of Cu-Be-Ag alloys in the process of decomposition of solid solution

Investigation of aging Cu-1.5% Be-2% Ag and Cu-1% Be-4% Ag alloys was carried out in this study by the methods of x-ray analysis of monocrystals, and electron microscopy. In the aging process at 218, 300, and 450C, laminar zones of Guinier-Preston, enriched with beryllium and silver atoms were formed. Entry of silver into the zones widens the upper temperature interval of the zone stage to 450C. With the increase of annealing time the metastable-phase was precipitated. The crystals of -phase are precipitated with orientation in the direction (100) in consequence of interactions of the fields of elastic stresses occurring around -precipitations, and periodic structure is formed in the alloy. The stable phase-CuBe and Ag was precipitated in the Cu-1% Be-4% Ag-alloy.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 21–25, August, 1972.     

Dynamics of spin state conversion processes in the solid state

Hyperfine Interactions - High spin (HS) ⇌ low spin (LS) conversions in transition metal complexes are nonradiative transitions between spin states. In this contribution, we present a study of...     

A simple 1,10-phenanthroline-based fluorescent receptor in solution and 1,10-phenanthroline in solid state for urea recognition

1,10-phenanthroline-based fluorescent chemosensor has been designed and synthesized for the recognition of urea and 1,3-dimethyl urea in CH₃CN. Interactions of this compound with urea and 1,3-dimethyl urea are studied with UV-visible and fluorescence spectroscopic methods. 1,10-phenanthroline was found to be capable of distinguishing urea from 1,3-dimethyl urea. The formation of a highly stable hydrogen bonded complex between 1,10-phenanthroline and urea was confirmed by single crystal X-ray diffraction analysis.     

INADEQUATE-CR experiments in the solid state.

Through-bond connectivity can be probed by J couplings. For effective two-spin systems, the INADEQUATE experiment is highly valuable in liquid-state spectroscopy. It is the purpose of this Communication to show that in-phase INADEQUATE-CR spectra, where the intensity is concentrated in only one line of the J splitted doublet, can be obtained from solid-state samples. The problem of the cancellation of nonresolved multiplet lines, as experienced typically in INADEQUATE spectra in the solid, is resolved and the (13)C spectra become simpler because the number of resonance lines is reduced. Furthermore, a gain in signal intensity by 2 can, theoretically, be achieved. We limit the discussion to two-spin systems. In the present context, a two-spin system is defined considering the J coupling only. When the dipolar coupling is also taken into account, the two-spin system will usually become a many-spin system, but in the present context this is not relevant.     

Nonlinear optics and the defect solid state

Abstract

The condition for the generation of second harmonics in the dipole approximation is that the nonlinear crystal medium lack a center of inversion. Conversely, a center of inversion precludes optical second harmonic generation. It is well known, however, that lattice defects introduced into a crystal may alter the local point symmetry in the medium, and in fact may convert local inversion symmetry to that which corresponds to a noncentrosymmetric point group. It is thus clear that selected defects in nonlinear media may be of interest for studying nonlinear optical processes which depend on the square of the electric field strength. The specific case of second harmonic generation employing spatially ordered FA-centers in alkali halide crystals is considered.     

Solution of the ground state problem of a solid solution for interaction potentials of finite radius

A method is proposed for finding the energetically favorable superstructure of a solid solution or a magnet on a pc-, bcc- and fcc-lattice. A hierarchical classification is made of the Brillouin zone points corresponding to energetically suitable superstructures.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 3–8, April, 1984.     

A multinuclear magnetic resonance study of intramolecular hydrogen bonding in some Schiff and Schiff-Mannich bases in solution and in the solid state

Two Schiff bases; N, N′-bis(5-bromosalicylidene)-1,2-diaminoethane, BS, and 7-[(1-{5-bromo-2-hydroxyphenyl} methylidene)amino]-4-methylcoumarin, Sc, and two appropriate Schiff–Mannich bases, N, N′-bis{5-bromo-3-[(diethylamino)methyl]salicylidene}-1,2-diaminoethane, BSM, and 7-[(1-{5-bromo-3-[(diethylamino)methyl]-2-hydroxyphenyl} methylidene)amino]-4-methylcoumarin, SMc, capable of intramolecular hydrogen bonding have been investigated by multinuclear magnetic resonance methods in both solid and liquid phases. In all of the compounds under investigation tautomeric equilibrium involving an intramolecular hydrogen bond has been found. The Schiff–Mannich bases, which can form two different kinds of H bonds at room temperature, form relatively weak H bonds with the imino nitrogen atoms. At low temperatures the tautomeric proton exchange becomes slow on the NMR time scale and both hydrogen-bonded forms can be observed by ¹H, ¹³C, and ¹⁵N NMR methods. In the solid state the tautomeric process is frozen and only one H-bonded form is present. On the basis of 13C and ¹⁵N CPMAS NMR spectra this is identified as the form with hydrogen bonds involving the imino groups. This conclusion is in good agreement with previous results obtained by X-ray diffraction methods.

The investigated Schiff bases (BS and Sc) form relatively weak H bonds. The proton position in the hydrogen bridge, estimated from ¹⁵N and ¹³C chemical shifts, is very similar in both the solution and solid phases. In chloroform solution the observed tautomeric equilibria are almost insensitive to a temperature change within the range 223 to 303 K.     

Luminescence kinetics characteristics of lead-containing aggregates dispersed in Rb0.95Cs0.05Cl solid state solution

The relaxation of the electron excitations in an insulating matrix such as the Rb_0.95Cs_0.05Cl solid solution containing CsPbCl₃ nanocrystals and single lead centers is studied. Modification of the spectral kinetic parameters of the CsPbCl₃ nanocrystals due to the quantum confinement is explored. Mechanism of the energy transfer from matrix to the nanocrystals is established. The luminescence of the Rb_0.95Cs_0.05C–Pb crystal is characterised by means of measurements with subnanosecond time resolution under synchrotron radiation excitation in the energy range of 3.7–20 eV at T=10 K.     

Study of the hydrogen solid solution in thulium

Solid solutions of hydrogen in thulium are investigated, mainly by X-ray determinations in the temperature range 20–500°C. Several observations lead us to distinguish between two variaties α and α¹. In the range of existence of the α¹ phase, below the transition temperature of 120°C, the hydrogen interstitials induce in the metal lattice a behaviour different from that of the α phase, as concerns the phase equilibrium, the additional resistivity, and the lattice anisotropy.Several simple models are proposed for the explanation of this anomaly, encountered also in other heavy rate earth-hydrogen systems.     

Primary solid state batteries

Low - cost, easily fabricated dry cells were constructed by gluing a composite conducting material or a metal sulphide on magnesium or aluminium foils, using a solid electrolyte made from polyvinyl - pyrolidone. Composite conducting materials consisted of polypyrrole and polyaniline incorporated into an inorganic or polymer matrix or cupric oxide incorporated into a styrene - butadiene copolymer matrix. The efficiency, energy densities and voltage values of the cells were in the range 0.5 – 18.3 mWh cm⁻³, 9 – 339 wh kg⁻¹ and 0.5 – 2.0 V, respectively. The energy densities of the cells were up to seventeen times more than the energy density of the PbO₂ -H₂SO₄ - Pb multiple charge / discharge system and up to ten times more than the energy density of the nickel / cadmium rechargeable cell. A dry cell composed solely from polymers was constructed with cell voltage 0.25 – 0.50 V and efficiency ranging from 0.07 to 0.13 mWh cm⁻³ ten times lower than other commercial cells. Paper presented at the 1st Euroconference on Solid State Ionics, Zakynthos, Greece, 11–18 Sept. 1994     

Influence of oxalate anions on manganese electrodeposition in sulfate solution

The influences of oxalate anions on manganese electrodeposition in sulfate solution were investigated on the basis of cathode current efficiency, characterization of SEM-EDX and XRD, solution chemistry calculation, thermodynamics and electrochemical test. The experimental results show that the range of (NH₄)₂C₂O₄ was adjusted from 0 mol/L to 4.8?×?10^?3 mol/L. And 1.5?×?10^?3 mol/L (NH₄) ₂C₂O₄ was suitably used with initial pH 7.0. The characterization of SEM indicates that oxalate anions can improve the morphology of electrodeposited films. The electrodeposited films containing manganese were characterized and determined by EDX and XRD. The solution chemistry calculation of catholyte and oxalate anions shows that the main active species are MnSO₄, Mn(SO₄)2? 2, Mn²⁺, Mn(SO₄)C₂O2? 4, MnC₂O 4, Mn(NH₃)²⁺, and C₂O2? 4. The reaction trend between C₂O2? 4 and Mn²⁺ ions is confirmed by computation of reaction energy. Electrochemical test analysis indicates oxalate anions increase the overpotentials of hydrogen evolution reaction and manganese electrodeposition.     

Photostimulated solid state reactions

This article gives a critical review of published results mainly on systems of the type (metal/chalcogenide glass), correlating these with phenomena occurring in (metal/photosensitive substance) systems. It is argued that the striking differences in the reaction curves of different pairs of (metal/photosensitive substance) are due only to the inherently different properties of the products of the ‘tarnishing’ reaction that occurs in each case. It is emphasized that the driving force of all the phenomena observed is actually this tarnishing reaction which occurs on illumination.     

Nonisothermal nucleation in a solid solution of CuCl in glass: Concentration effect upon heating of the solid solution

Physics of the Solid State - The influence of the heating rate of a solid solution of CuCl in glass on the size distribution of the produced CuCl nanoparticles is studied. The distribution curves...     

Quasi-particles method in solid solution theory

In this paper the method of cluster components is treated for calculations of cation exchange. It gives the dependence of the properties on the equilibrium constant. The interdependence of the method of cluster components with the quasi-chemical approximation is discussed. Possible applications of this technique are illustrated for spinel solid solutions.     

Thermoluminescence and long afterglow of adenine in the solid state

The low-temperature thermoluminescence and the long afterglow of adenine in the solid state are studied after irradiation with UV light and X-rays. The glow peaks are due to the quasi-continuous energy spectrum of trapping levels. The hyperbolic decay law of the long afterglow is interpreted as a tunnel recombination luminescence between pairs of localized charged species. Both tunneling and temperature-dependent processes occur at the same trapping sites which are apparently structural defects.     

Initial decoherence in solid state qubits

We study decoherence due to low frequency noise in Josephson qubits. Non-Markovian classical noise due to switching impurities determines inhomogeneous broadening of the signal. The theory is extended to include effects of high-frequency quantum noise, due to impurities or to the electromagnetic environment. The interplay of slow noise with intrinsically non-Gaussian noise sources may explain the rich physics observed in the spectroscopy and in the dynamics of charge based devices.