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Energy E (energy + e)
Selected AbstractsExponentially accurate quasimodes for the time-independent Born,Oppenheimer approximation on a one-dimensional molecular systemINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 5 2005George A. Hagedorn Abstract We consider the eigenvalue problem for a one-dimensional molecular-type quantum Hamiltonian that has the form where h(y) is an analytic family of self-adjoint operators that has a discrete, nondegenerate electronic level ,(y) for y in some open subset of ,. Near a local minimum of the electronic level ,(y) that is not at a level crossing, we construct quasimodes that are exponentially accurate in the square of the Born,Oppenheimer parameter , by optimal truncation of the Rayleigh,Schrödinger series. That is, we construct an energy E, and a wave function ,,, such that the L2 -norm of ,, is ,,(1) and the L2 -norm of (H(,) , E,),, is bounded by , exp(,,/,2) with , > 0. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source] Dielectric properties of (NH4)2SO4 crystals in the range of electronic excitationsJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2009B. Andriyevsky Spectra of the real and imaginary parts of the pseudo-dielectric permittivity, ,,1,(E) and ,,2,(E), of ferroelectric ammonium sulfate crystals, (NH4)2SO4, have been measured in the range of electronic excitations 4.0 to 9.5,eV by ellipsometry using synchrotron radiation. Temperature dependences of the corresponding susceptibilities, ,,1,(T) and ,,2,(T), obtained for the photon energy E = 8.5,eV, related to excitations of oxygen p -electrons, reveal sharp peak-like temperature changes near the Curie point TC = 223,K. The large temperature-dependent increase of the imaginary part of the susceptibility ,2(T), together with a simultaneous decrease of the real part of the susceptibility ,1(T), take place at the phase transition. These anomalies have been ascribed mainly to the SO4 group of the crystal structure. [source] Explosion energies, nickel masses and distances of Type II plateau supernovaeMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2003D. K. Nadyozhin ABSTRACT The hydrodynamical modelling of Type II plateau supernova (SNIIP) light curves predicts a correlation between three observable parameters (plateau duration, absolute magnitude and photospheric velocity at the middle of the plateau) on the one hand, and three physical parameters (explosion energy E, mass of the envelope expelled and pre-supernova radius R) on the other. The correlation is used, together with adopted distances from the expanding photosphere method, to estimate and R for a dozen well-observed SNIIP. For this set of supernovae, the resulting value of E varies within a factor of 6 (0.5 ,E/1051 erg , 3), whereas the envelope mass remains within the limits . The pre-supernova radius is typically 200,600 R,, but can reach ,1000 R, for the brightest supernovae (e.g. SN 1992am). A new method of determining the distance of SNIIP is proposed. It is based on the assumption of a correlation between the explosion energy E and the 56Ni mass required to power the post-plateau light curve tail through 56Co decay. The method is useful for SNIIP with well-observed bolometric light curves during both the plateau and radioactive tail phases. The resulting distances and future improvements are discussed. [source] The energy cascade from warm dark matter decaysMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2008M. Valdés ABSTRACT We use a set of Monte Carlo simulations to follow the cascade produced by a primary electron of energy Ein in the intergalactic medium. We choose Ein= 3,10 keV as expected from the decay of one of the most popular warm dark matter (WDM) candidates, sterile neutrinos. Our simulation takes into account processes previously neglected such as free,free interactions with ions and recombinations, and uses the best available cross-sections for collisional ionizations and excitations with H and He and for electron,electron collisions. We precisely derive the fraction of the primary electron energy that heats the gas, ionizes atoms and produces line and continuum photons as a function of the ionization fraction. Handy fitting formulae for all the above energy depositions are provided. By keeping track of the individual photons, we can distinguish between photons in the Ly, resonance and those with energy E < 10.2 eV that do not interact further with gas. This separation is important because a Ly, background can heat or cool the gas depending on the nature of the photons, and can have effects on the 21-cm radiation emitted by neutral H, which will probably become detectable at z > 6 in the near future by the next generation radio interferometers. [source] Structural changes in Si crystals exposed to chemical etching and ion implantationPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2009I. Fodchuk Abstract Results of X-ray diffraction studies on structural changes in Si crystals caused by chemical etching for 40,s in HF, HNO3 solution and phosphorus-ion implantation with the energy E,=,100,keV and dose D,=,8,×,1014,cm,2 are represented. Two- and three-crystal X-ray diffractometry methods are used for a quantitative assessment of structural changes occurring in the near-surface crystal layers. Analysis of experimental rocking curves was made with the use of different approaches developed on the basis of kinematic and dynamic theory of X-ray scattering in the imperfect crystals. A model of possible system of structural defects in the near-surface silicon layers modified by chemical etching and ion implantation is proposed. The model accounts for the availability of respective sizes and concentrations of spherical and disc-shaped cluster formations, dislocation loops. [source] The effect of aging on the dark conductivity and 1/f noise in hydrogenated microcrystalline silicon thin filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010M. Güne Abstract Aging hydrogenated microcrystalline silicon in air is found to affect both the dark conductivity and the 1/f noise. For a sample with a crystalline volume fraction of 0.39, the conductivity decreased by three orders of magnitude at 20 °C after short-term (10,20 hrs) exposure to air. The conductivity recovered after annealing to 160 °C. Long-term exposure (2 years) resulted in a permanent decrease by a factor of 16 at 20 °C even after annealing. Long-term aging also increased the conductivity activation energy from 0.193 eV to 0.342 eV. After short-term aging and below the annealing temperature, the conductivity prefactor ,0 and the activation energy E, follow a Meyer-Neldel type of relation. Conductance fluctuations measured for annealed and aged states show all the expected characteristics of 1/f noise. The spectra fit a power law with slope -1; the slope is not affected by temperature or aging. The magnitude of the noise decreases with temperature after aging, but by much less after annealing. A simple analysis of the product of conductivity and noise magnitude can be used to estimate the free carrier mobility (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A new look at the derivation of the Schrödinger equation from Newtonian mechanicsANNALEN DER PHYSIK, Issue 6 2003L. Fritsche Abstract We present a modified version of Nelson's seminal paper on the derivation of the time-dependent Schrödinger equation which draws on the equation of motion of a particle that moves under the influence of a classical force field and additional stochastic forces. The emphasis of our elaboration is focused on the implication of allowing stochastic forces to occur, viz. that the energy E of the particle is no longer conserved on its trajectory in a conservative force field. We correlate this departure , E from its classical energy with the energy/time uncertainty relation where , t is the average time for , E to persist. The stability of atoms, the zero-point energy of oscillators, the tunneling effect and the diffraction at slits are shown to be directly connected with the occurrence of such energy fluctuations. We discuss and rederive Nelson's theory entirely from this point of view and generalize his approach to systems of N particles which interact via pair forces. Achieving reversibility in a description of particle motion that is akin to Brownian motion, represents a salient point of the derivation. We demonstrate that certain objections raised against Nelson's theory are without substance. We also try to put the particular worldview of this version of stochastic quantum mechanics into perspective with regard to the established Copenhagen interpretation. [source] Mechanism study on carbon reducing reaction in the preparation process of strontium carbonate (SrCO3)ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Jun Meng Abstract The mechanism for preparation of strontium carbonate (SrCO3) by the method of carbon reducing reaction is studied in this paper. Based on the mass ratio of SrSO4/C = 1.5 for this reaction, thermodynamics and kinetics calculation are conducted and also verified by TG-DSC experimental methods. For each side reaction, the changes of standard molar Gibbs function at proposed temperature are calculated through Gibbs-Helmholtz, Van't Hoff and Kirchhoff equations. TG-DSC data are used to explore the mechanism of the reaction, and to calculate the apparent activation energy and reaction orders. It has been demonstrated by TG and DSC thermal analysis for the whole reducing reaction that the apparent activation energy E is 350.6 and 307.3 kJ·mol,1, and the reaction orders n are 0.91 and 0.88, respectively. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Link, twist, energy, and the stability of DNA minicirclesBIOPOLYMERS, Issue 2 2003Kathleen A. Hoffman Abstract We describe how the stability properties of DNA minicircles can be directly read from plots of various biologically intuitive quantities along families of equilibrium configurations. Our conclusions follow from extensions of the mathematical theory of distinguished bifurcation diagrams9, 21 that are applied within the specific context of an elastic rod model of minicircles. Families of equilibria arise as a twisting angle , is varied. This angle is intimately related to the continuously varying linking number Lk for nicked DNA configurations that is defined as the sum of Twist and Writhe. We present several examples of such distinguished bifurcation diagrams involving plots of the energy E, linking number Lk, and a twist moment m3, along families of cyclized equilibria of both intrinsically straight and intrinsically curved DNA fragments. © 2003 Wiley Periodicals, Inc. Biopolymers 70: 145,157, 2003 [source] Non-isothermal Decomposition Reaction Kinetics of the Magnesium Oxalate DihydrateCHINESE JOURNAL OF CHEMISTRY, Issue 3 2006Jian-Jun Zhang Abstract The thermal decomposition of the magnesium oxalate dihydrate in a static air atmosphere was investigated by TG-DTG techniques. The intermediate and residue of each decomposition were identified from their TG curve. The kinetic triplet, the activation energy E, the pre-exponential factor A and the mechanism functions f(,) were obtained from analysis of the TG-DTG curves of thermal decomposition of the first stage and the second stage by the Popescu method and the Flynn-Wall-Ozawa method. [source] The high-density electron gas: How momentum distribution n (k) and static structure factor S(q) are mutually related through the off-shell self-energy , (k, ,)ANNALEN DER PHYSIK, Issue 10 2010P. Ziesche For the spin-unpolarized uniform electron gas, rigorous theorems are used (Migdal, Galitskii-Migdal, Hellmann-Feynman) which allow the calculation of the pair density, g(r), or equivalently its Fourier transform, the static structure factor, S(q), from the dynamical 1-body self-energy , (k, ,), supposing the self-energy is (approximately) known as a functional, depending on the kinetic energy of a single electron, t(k), and on the bare Coulomb repulsion between two electrons, v(q). With the momentum distribution, n(k), and with the kinetic (t) and potential (v) components of the total energy e = t + v, the respective steps are: (i) , (k, ,) , n(k) , t, (ii) , (k, ,) , v, (iii) t + v = e, S(q). How this general scheme works in detail is shown explicitly for the high-density limit (as an illustration). For this case the ring-diagram partial summation or random-phase approximation applies. In this way, the results of Macke (1950), Gell-Mann/Brueckner (1957), Daniel/Vosko (1960), Kulik (1961), and Kimball (1976) are summarized in a coherent manner. Besides, several identities were brought to the light, e.g. the Kimball function for S(q) proves to be identical with Macke's momentum transfer function I(q) for e. [source] | ||||||||||||||||||||||