Showing papers on "Charge density published in 1974"
TL;DR: In this paper, the anomalous properties of polytypes of charge-density waves, their periodic structure distortions, and the superlattices they induce are attributed to charge density waves.
Abstract: The previously termed "anomalous" properties of the various polytypes of ${d}^{1}$ Ta${\mathrm{S}}_{2}$, Ta${\mathrm{Se}}_{2}$, etc. are attributed to charge-density waves, their periodic structure distortions, and the superlattices they induce.
426 citations
TL;DR: In this paper, the equilibrium bipolar charge distribution of aerosols has been measured using monodisperse DOP (di-octyl phthalate) particles of 0.53, 0.55, and 1.17 μm diameter.
170 citations
TL;DR: In this article, a method to extract nuclear charge densities from elastic electron scattering data without using model distributions is proposed, which is based on the assumption that no structures in ϱ ( r ) having a width smaller than Γ are admitted.
158 citations
PARC1
TL;DR: In this article, a calculation of lattice dynamical effective charges by Bennett and Maradudin is shown to be based upon an incorrect expression for the electric polarization produced by displacement of the atoms.
Abstract: A calculation of lattice dynamical effective charges by Bennett and Maradudin is shown to be based upon an incorrect expression for the electric polarization produced by displacement of the atoms. The basic point is that the polarization of a crystal cannot be derived solely in terms of the charge density in a unit cell in an infinite periodic crystal. The correct polarization is most readily evaluated from well-known finite-wave-vector expressions.
154 citations
TL;DR: In this paper, les abondances relatives des elements de charge 4 ≤ Z ≤ 28 and le spectre d'energie absolu de ces elements sont determined.
Abstract: Une analyse de la composition elementaire du rayonnement cosmique est realisee a partir des donnees du satellite HEAO-3-C2. Les abondances relatives des elements de charge 4 ≤ Z ≤ 28 et le spectre d'energie absolu de ces elements sont determines.
124 citations
TL;DR: In this paper, the Fourier-Bessel expansion of the nuclear ground state and transition charge density is used to deduce the charge distributions and the moments as well as corresponding errors, which originate from the uncertainties in the measured data and from the lack of knowledge about the large- q behaviour of the form factors.
123 citations
TL;DR: In this article, the deformation structure of 1T TaS2 was interpreted in terms of charge density waves arising from a Kohn anomaly, and there is good agreement between the observed periodicity of the lattice distortion and the value predicted from a Fermi surface based on recent band structure calculations.
Abstract: Diffraction studies have enabled the deformation structure of 1T TaS2to be interpreted in terms of charge density waves arising from a Kohn anomaly. There is good agreement between the observed periodicity of the lattice distortion and the value predicted from a Fermi surface based on recent band structure calculations.
114 citations
101 citations
TL;DR: In this article, the core electron binding energies for analogous compounds of carbon, silicon, and germanium have been measured by X-ray photoelectron spectroscopy in the gas phase.
Abstract: Core electron binding energies for analogous compounds of carbon, silicon, and germanium have been measured by X-ray photoelectron spectroscopy in the gas phase. The chemical shifts have been correlated by the electrostatic potential equation using charge distributions from extended Huckel theory, CNDO/2, and an electronegativity equalization method. The data can be rationalized without any consideration p..pi -->..d..pi.. or p(pi)..-->..d(pi) in the silicon and germanium compounds.
87 citations
TL;DR: In this article, the heterogeneity of the interlayer cation density and the corresponding mean layer charge density due to isomorphous substitution have been determined for six montmorillonite samples by considering the transition of a monolayer to a double layer complex with alkylam-monium ions.
Abstract: The heterogeneity of the interlayer cation density and the corresponding mean layer charge density due to isomorphous substitution have been determined for six montmorillonite samples. This has been achieved by considering the transition of a monolayer to a double layer complex with alkylam- monium ions. The transition is related to the interlayer cation density, together with the variation of the apparent spacings, which in turn is related to the composition of this two-component mixture. All the samples showed a heterogeneous interlayer cation distribution and a differing mean charge den- sity.
86 citations
TL;DR: In this article, the Coulomb energy contribution to the interaction energy is calculated directly from the charge distribution of the nuclei and the assumed electron density, and the non-Coulombic part of the energy contribution is calculated from the electron density using the electron gas energy expression in terms of the local electron density.
Abstract: Interaction potentials of many ion pairs are calculated using the model presented in our previous paper [J. Chem. Phys. 56, 3122 (1972)]. In the calculation of the interactions of two ions, the electron density of the combined system of the ions is assumed to be equal to the sum of the two separate ionic electron densities. The Coulomb energy contribution to the interaction energy is calculated directly from the charge distribution of the nuclei and the assumed electron density. The non‐Coulombic part of the interaction energy is calculated from the electron density using the electron gas energy expression in terms of the local electron density. The ions treated are the alkali, the alkaline earth, and the halide ions. The calculated ion‐ion interaction potentials are applied to the theory of alkali halide and alkaline earth dihalide molecules. The predicted molecular bond energies, bond lengths, and vibration frequencies agree quite well with existing experimental data.
TL;DR: In this article, an ab initio study of the electronic structure and properties of magnesium oxide was carried out and the self-consistent charge density in the crystal was obtained by solving the Adams-Gilbert local-orbitals equations.
Abstract: We have carried out an ab initio study of the electronic structure and properties of magnesium oxide. The self-consistent charge density in the crystal is obtained by solving the Adams-Gilbert local-orbitals equations. The Fock operator is then constructed with nonlocal exchange and the energy bands are computed. These bands are then corrected for correlation effects. Long-range contributions are calculated by means of the electronic-polaron model. Short-range contributions are found to be large as predicted recently by the authors for fluorides, oxides, and nitrides in general. The final energy bands are in agreement with optical and x-ray data for the gaps and other transition energies. We predict an indirect minimum gap in MgO. The structure in the uv optical spectra is reproduced by our joint density of states and ${\ensuremath{\epsilon}}_{2}(\ensuremath{\omega})$ calculation. We compare our results with previous theoretical studies in the empirical-pseudopotential scheme and the Hartree-Fock-Slater approximation. MgO is the first II-VI compound and the first oxide to be treated in the Hartree-Fock scheme.
TL;DR: In this paper, the Coulombic energy contribution to the interaction energy is calculated directly from the charge distribution of the nuclei and the assumed electron density, and the non-Coulombic part of the energy contribution is calculated from the electron density by integrating the uniform electron gas energy expression over the local electron density.
Abstract: Interactions of the rare gas atoms with some alkali and halide ions are treated using the model presented in our previous paper [J. Chem. Phys. 56, 3122 (1972)]. In the calculation of the interactions of an atom and an ion, the electron density of the combined system is assumed to be equal to the sum of the two separate electron densities. The Coulombic energy contribution to the interaction energy is calculated directly from the charge distribution of the nuclei and the assumed electron density. The non‐Coulombic part of the interaction energy is calculated from the electron density by integrating the uniform electron gas energy expression over the local electron density. The calculated potential curves agree very well with available experimental results over the entire repulsive wall. At larger distances, the model fails, because in its present form it does not include induction forces.
TL;DR: In this paper, the authors measured the injection and propagation of charge in the Si3N4 film of an MNOS structure caused by a pulsed electric field and found that the spatial distribution of the trapped electrons extends deep into the Si 3N 4 film.
Abstract: A new experimental technique is described, which measures the injection and propagation of charge in the Si3N4 film of an MNOS structure caused by a pulsed electric field. Contrary to the widely held contention that the electrons injected from the Si are trapped in and very near the SiO2–Si3N4 interface, a contention resulting from the assumption that the trap density near this interface usually far exceeds the number of injected electrons, this work finds that the spatial distribution of the trapped electrons extends deep into the Si3N4 film. In fact, the centroid of the spatial distribution of the trapped electrons in a Si3N4 film ≃500 A thick can be as much as 150 A or more from the SiO2–Si3N4 interface, indicating that the span of the distribution extends across almost the entire thickness of the film with an average density of trapped electrons in the order of 3 × 1018/cm3. It is shown that, in general, the centroid of the trapped charge distribution in the Si3N4 film of a given device structure is a...
TL;DR: In this paper, the influence of charge exchange on the energy loss fluctuations of ions has been studied using experimental charge exchange cross-sections and the results indicate that the contribution of the charge exchange to energy loss fluctuation can be a major factor for lower energies.
TL;DR: In this article, the self-consistent electronic energy band structure of a 13-layer (001) film of lithium has been calculated using the method described previously, and the crystalline potential is described in terms of a nonlocal pseudopotential, with exchange-correlation effects treated by the local approximation used in the Lang-Kohn jellium studies.
Abstract: The self-consistent electronic energy band structure of a 13-layer (001) film of lithium has been calculated using the method described previously. The crystalline potential is described in terms of a nonlocal pseudopotential, with exchange-correlation effects treated in terms of the local approximation used in the Lang-Kohn jellium studies. The planar averages of both charge density and local part of the potential exhibit Friedel oscillations that are appreciably greater than a superposition of the jellium results on the bulklike envelopes in the inner selvage region; in the outer selvage the planar average of the potential agrees well with the jellium result. The (unoccupied) surface state appearing in the $\overline{X}$ gap of the two-dimensional band structure in our initial communication has descended almost to the bulk band below, and in its place a surface state of complementary planar symmetry has descended into the $\overline{X}$ gap from the bulk band above.
TL;DR: In this article, the SCF-X α-SW method was used to carry out an approximate Hartree-Fock calculation on the electronic structure on UF6−, where the charge density within the atomic spheres was analyzed into its angular momentum components and the first two excited electronic states were computed.
Abstract: The SCF‐X α‐SW method is used to carry out an approximate Hartree‐Fock calculation on the electronic structure on UF6−. The charge density within the atomic spheres is analyzed into its angular momentum components and the first two excited electronic states are computed.
TL;DR: In this article, the influence of the electric field induced by the overlapping of the two double layers is taken into account in the Debye-Huckel approximation by introducing a dimensionless parameter (α = { 1 + (es/e′) ϰd}−1, e and e′ being the dielectric constants of the solution and of the plate, respectively, ϰ theDebye Huckel parameter and d the thickness of a plate.
Abstract: The diffuse double layer interaction between two parallel similar plates with constant surface charge density in a symmetrical electrolyte solution is considered. The influence of the electric field which may be induced within the plates by the overlapping of the two double layers is taken into account in theDebye-Huckel approximation by introducing a dimensionless parameter (α = { 1 + (es/e′) ϰd}−1, e and e′ being the dielectric constants of the solution and of the plate, respectively, ϰ theDebye-Huckel parameter and d the thickness of the plate. The solution of the non-linearPoisson-Boltzmann equation are also obtained for the case of thick plates.
TL;DR: In this paper, the electronic band structures and charge densities of NbC and NbN were analyzed and the major contribution to the charge density of the bands near the Fermi energy comes from C or N $4p$ states.
Abstract: We present nonlocal-pseudopotential calculations of the electronic band structures and charge densities of NbC and NbN. The major contribution to the charge density of the bands near the Fermi energy comes from C or N $4p$ states. The charge density for the first partially filled Nb $4d$ band and the shape of the Fermi surface for this band are also discussed.
01 Jan 1974
TL;DR: In this paper, a two-level-atom model is used to model the green function of an exciton coupled with Phonons in molecular Crystals and the role of free radicals in electrical conductivity.
Abstract: Opening Address.- Charge Carriers.- Voltage Dependence of Unipolar Excess Bulk Charge Density in Organic Insulators.- Geminate Charge-Pair Recombination in Molecular Crystals.- Various Detrapping Processes in Anthraquinone-Doped Anthracene Crystal.- UV Excitation of Anthracene.- Photoconduction and Emission of Phthalocyanine in the Near Infrared.- Optical and Electron Paramagnetic Properties of Radicals in Naphthalene and Anthracene Crystals.- Contribution of Free Radicals to Electrical Conductivity.- Theory.- Green Function of an Exciton Coupled with Phonons in Molecular Crystals.- Theory of Frenkel Excitons Using a Two-Level-Atom Model.- Crystallization.- Glass-Forming Photoconductive Organic Compounds. I. Phase Change and Single Crystal Growth of 1,3-Diphenyl-5-(p-Chlorophenyl)-Pyrazoline.- Semi conductive Coordination Polymers: Dithiooxamides Copper Compounds.- Growth and Purification of Phthalocyanine Polymorphs.- Transport in Amorphous State and Polymers.- Mobility Measurements in Polymers by Pulsed Electron Beams.- Photoconductivity of Poly-N-Vinylcarbazole.- Sensitized Photocurrent in Dye-Deposited Poly-(N-Vinylcarbazole).- Charge Injection and Transport in Disordered Organic Solids.- Charge Transport in TNF:PVK and TNF: Polyester Films and in Liquid, Amorphous and Crystalline TNF.- Superconductivity.- The Problem of Superconductivity in Organic and Organo-Metallic Compounds.- Comments on the Metallic Conductivity in (TTF)(TCNQ) Complex.- Design and Study of 1-Dimensional Organic Conductors I: The Role of Structural Disorder.- Design and Study of 1-Dimensional Organic Conductors II: TTF-TCNQ and Other Organic Semimetals.- Solid Molecular Complexes.- The Structures and Properties of Solid Molecular Complexes and Radical Salts: A Brief Review of Recent Studies in Japan.- Microwave Dielectric Constants of Solid Molecular Complexes.- Electrical and Optical Properties of the Phenothiazine-Iodine and Related Complexes.- Author Index.
TL;DR: In this article, the small signal admittance of a junction device in the presence of deep lying majority carrier traps is obtained as a solution to a simple differential equation (dC/dχ) = (C2/e)−(ρac/ψac), where C Y/jω is the complex capacitance, x is the distance within the depletion region from the neutral bulk semiconductor, ρac is the a.c. incremental change in charge density at χ when the bias is incremented by ψac.
Abstract: The small signal admittance, Y, of a junction device, in the presence of deep lying majority carrier traps, is obtained as a solution to a simple differential equation (dC/dχ) = (C2/e)−(ρac/ψac), where C Y/jω is the complex capacitance, x is the distance within the depletion region from the neutral bulk semiconductor, ρac is the a.c. incremental change in charge density at χ when the bias is incremented by ψac. This equation can be numerically integrated with one boundary condition, the flat band capacitance of the bulk semiconductor. An analytic solution to the above differential equation is possible over a wide frequency range without the use of a truncated space charge approximation. The admittance of one half of a junction device can then be modelled by a 3p + 1 lumped element equivalent circuit involving 3p + 2 device parameters, where p is the number of species of deep lying majority carrier traps that are virtually unionized in the bulk. These circuit elements bear simple direct relationships to the deep level parameters. Impedance vs frequency measurements at a single bias and temperature yield only 2p + 1 equations and are not sufficient to define the elements uniquely. One therefore needs p + 1 additional equations for a unique synthesis. We also show how additional equations can be obtained from impedance vs voltage or temperature measurements.
CERN1
TL;DR: In this article, the results of the muonic isomer shifts are compared with calculations based on various nuclear models, and new information can be deduced from a comparison, which can be used to evaluate electron density differences in rare earth compounds.
TL;DR: In this article, the radial transition charge density and the reduced transition probability of the 3 − level in 208 Pb were determined model independently from inelastic e − scattering cross sections.
TL;DR: In this paper, a discrete ambiguity of ρ ( r ) at small radii is discovered, and an analysis of 39 K and 48 Ca data does not allow to remove this ambiguity.
TL;DR: A series of Cu(II) reduced charge montmorillonites (RCM) of varying charge reduction has been prepared by exchange of the parent Li(1)-Na(I) mineral with CuC12 in 95 per cent ethanol solution as discussed by the authors.
Abstract: A series of Cu(II) reduced charge montmorillonites (RCM) of varying charge reduction has been prepared by exchange of the parent Li(1)-Na(I) mineral with CuC12 in 95 per cent ethanol solution. The Cu(II) exchange capacity, as determined by Na(I) exchange in 1 : 1 (v/v) ethanol-water, is a linear func- tion of the fraction of Li(I) initially present on the exchange sites, F. Selective Cu(II)-saturation on internal and external sites was achieved at maximum charge reduction (F = 1-0). Water sorption isotherms and (001) basal spacings are interpreted in terms of an increasing tendency toward interlayer collapse with increasing charge reduction. Because of the higher hydration energy of the Cu(II) ion, however, the frac- tion of non-expansible interlayers at a given F value is lower than those present in the corresponding Li(I)-Na(I) RCM. Electron spin resonance spectra of oriented samples show that under air-dried condi- tions (ca. 40 per cent r.h.) the predominant Cu(II) species present, whether on internal or external sites, is the planar Cu(H20) 2+ ion. The symmetry axis of the ion is oriented perpendicular to the a-b plane of the silicate sheets. In the presence of a full partial pressure of water, the Cu(II) ions on the external sites and those which are in expansible interlayers become totally hydrated Cu(H20)62§ and tumble rapidly. The Cu(H20)) + ions in non-expansible layers retain their restricted orientation on the silicate surface. Some general conclusions have been drawn regarding the nature of charge distribution in the mineral.
TL;DR: In this article, photoemission measurements on amorphous and trigonal Te have been carried out using density of states and charge density calculations, and the results result in new insights into the possible structural nature of the Amorphous phase.
01 Dec 1974
TL;DR: In this paper, the linearity of the electrical signal injection into charge-coupled devices (CCDs) has been studied by measuring the generated higher harmonic components of a sinusoidal input.
Abstract: The linearity of the electrical signal injection into charge-coupled devices (CCDs) has been studied by measuring the generated higher harmonic components of a sinusoidal input. Results obtained with various injection methods and device geometries have been compared. Best results, with all harmonic components more than 40 dB below the fundamental, have been obtained for surface channel devices with a potential equilibrium method in which the signal is applied to a second input gate, while the first input gate is held at a dc reference potential. Bulk channel devices show more distortions, which is a consequence of the changing charge distribution in the channel with varying channel potential.
TL;DR: In this article, an analysis leading to some basic relations is performed on a one-dimensional model of a buried-channel charge-coupled device (CCD) and the maximum charge-carrying capacity is discussed and compared to that for a surface-type CCD.
Abstract: An analysis leading to some basic relations is performed on a one-dimensional model of a buried-channel charge-coupled device (CCD). Expressions for the charge distribution, potential, channel thickness, and location are obtained. These enable the effects of varying the device structural parameters, as well as the gate voltage and signal charge, to be examined very simply. The maximum charge-carrying capacity is discussed and compared to that for a surface-type CCD. Furthermore, the analysis is extended to a device with a nonuniformly doped semiconductor layer.