Magnetic field dependencies of the critical current and of the resonant modes of dc SQUIDs fabricated from superconductors with s + id order-parameter symmetries

The magnetic field dependencies of the critical current and of the self-induced resonant modes of dc SQUIDs fabricated from superconductors with s + id order parameter symmetries are calculated. Combining the complementary results of the two dependencies, an unambiguous determination of the ratio of the s and d wave components is possible. Two cases of SQUID configurations are analyzed for which the flux coupled to the two Josephson junctions of the dc SQUID is either negligible or significant.     

Desorptions- und Reaktionskinetik der Erdalkalien Calcium und Strontium mit Chlor an Wolfram. Part II: Kinetics of the Elementary Steps of the Surface Reaction M + Cl ⇌ MCl (M = Ca,Sr)

Desorption- and Reactionkinetics of the Alkaline Earth Elements Calcium and Strontium with Chlorine on a Tungsten Surface — Part II: Kinetics of the Elementary Steps of the Surface Reaction M + Cl ? MCl (M = Ca, Sr) Utilizing pulsed molecular-beam-technique the kinetics of desorption of Strontium, Calcium, and Chlorine as well as that of the molecules SrCl and CaCl, which are formed at the hot tungsten surface, was investigated. Thereby, the following values were obtained for the activation energies of desorption: ? = (3.76 ± 0.05) eV, ? = (3.32 ± 0.07) eV, ? = (4.16 ± 0.05) eV, ? = (4.2 ± 0.3) eV and ? = (3.9 ± 0.3) eV. Combining these results with the steady-state-results from part I [1] the temperature dependency of the rate constants of dissociation and recombination of MCl-molecules at the tungsten surface could be determined. The values obtained for the dissociation energies D of SrCl and CaCl on tungsten are (0.5 ± 0.5) eV and (0.3 ± 0.5) eV, respectively. The molecules are stabilized on the surface by the activation barrier for dissociation D? only, which was found to be (2.8 ± 0.5) eV for SrCl and (2.3 ± 0.5) eV for CaCl.     

Experimentelle Untersuchungen zur Ionisierung und Umladung von Alkanolen durch 6-25 keV Wasserstoffionen

Experimental Investigations of Ionisation and Charge-transfer of Alcohols by 6-25 keV Hydrogen Ions Ionisation and charge-transfer cross sections were measured for the interaction of H⁺, H and H ions (in the energy range 6-25 keV) with alcohols (methanol-octanol). The cross sections depend significantly on the target molecular structure like molecular length, ionisation potential, polarizability and atomic bonds in the target molecule.     

Desorptions- und Reaktionskinetik der Erdalkalien Calcium und Strontium mit Chlor an Wolfram. Teil I: Chemisches Gleichgewicht der Oberflächenreaktion M + Cl = MCl im stationären Zustand (M = Ca,Sr)

Desorption- and Reactionkinetics of the Alkaline Earth Elements Calcium and Strontium with Chlorine on a Tungsten Surface — Part I: Chemical Equilibrium of the Surface Reaction M + Cl ? MCl in the Steady State (M = Ca, Br) Utilizing positive and negative surface ionization the reaction M + Cl = MCl (M = Ca, Sr) was studied at a hot tungsten surface under steady state conditions. Comparing the results obtained either by simultaneous M- and Cl₂ -exposures or by MCl₂ -exposure the existence of chemical equilibrium could be confirmed for the reaction in the temperature interval 1600 K.2000 K; at higher temperatures this equilibrium can be disturbed considerably by the desorption of the reacting components. From the experimental results we obtained under conditions of chemical equilibrium the energy of dissociation of MCl-molecules in the gasphase (D = (3.9 ± 0.15) eV, D = (4.2 ± 0.15)eV) and in the case of a strong disturbance of the equilibrium the difference between the activation energies of desorption and of dissociation of MCl-molecules on the surface (? - D? = (1.6 ± 0.2) eV, ? - D? = (1.4 ± 0.2) eV).     

Hyperfine Structure of the Configuration lll

The matrix elements for the hyperfine structure of the configuration lll in SL-Kopplung are expressed as linear combinations of the electron coupling constants α_li(10), α_li(01), α_li(12).     

Anwendung der GRYZINSKY-Theorie zur Berechnung der Ionisierungs- und Umladungwirkungsquerschnitte für die Wechselwirkung von Wasserstoffionen und Alkanolmolekülen

An Application of GRYZINSKY -theory to Calculations of Ionisation and Charge-transfer Cross Sections for the Interaction of Hydrogen Ions with Alcohol Molecules Ionisation and charge-transfer cross sections were calculated for the interaction of H⁺, H and H ions (energy range 5-25 keV) with alcohols (methanol-butanol). A modified GRYZINSKY approximation is used for the calculation of the cross sections. The calculated values have been compared with experimental determined cross sections. The agreement between experimental results and theoretical results is satisfactory.     

Electron Emission from Clean Solid Surfaces by Fast Ions

Total backward electron yields from 27 elemental, non-crystalline, clean solids were measured during bombardment by H⁺-, H-, H-, He⁺- and Ar⁺-ions in the energy range from 100 keV to 800 keV. The yields were found to exhibit an oscillatory dependence on the atomic number of the target material correlated with the periods of the periodic system. These Z₂-oscillations are relatively insensitive to the type of projectile and the impact energy at the high projectile energies of this experiment. Present theories of electron emission cannot explain the main experimental results. The reasons for this failure are discussed.     

On a Mechanical Model of the Bopp-Podolsky Potential

For an arbitrary given distribution of dislocations and disclinations the general state of stress of a mechanical continuum is investigated. The medium is reacting with stresses and momentum stresses (Cosserat continuum). By means of differential geometry it is shown that the deformations _ik and ?_ik of two arbitrary materials with identical distributions of defects differ merely by a displacement field u_i(x^r, t). If _ik are the eigendeformations of an isotropic medium, then in the linear theory the field u_i of a Cosserat continuum can be separated from _ik. If the problem is static the u_i obey the potential equation of Bopp-Podolsky electrodynamics. As source only torsion (dislocations and torsion of disclinations) is acting. To give an example the field u_i for straight dislocations and disclinations is calculated. Especially the problem of singularities is discussed.     

Sea Level Muon Spectrum Derived from Bugaev Model

The pion and kaon spectra in the atmosphere are derived from primary nucleon spectrum determined by GRIGOROV et al.; they satisfy the relations N(E_π) dE_π = 0.187 EdE_π and N(E_k) dE_k = 0.017 E dE_k, respectively. By using the pion-kaon atmospheric diffusion equation the sea level muon spectrum is calculated and the result compared with the magnetic spectrograph data of ALLKOFER et al. and AYRE et al.     

DC Conductivity and Peierls instability in the quasi-one-dimensional organic charge density wave conductor (fluoranthene)2X

Due to the high anisotropy of the dc conductivity (σ_|/σ_⊥ ≈ 10⁴) the organic conductor (fluoranthene)₂X can be regarded as a model system for studying the Peierls instability in quasi-one-dimensional systems. The temperature dependence of the dc conductivity σ_| (T) along the highly conducting crystal axis exhibits the typical behaviour of a quasi-one-dimensional metal with a Peierls transition at about 180 K to a charge density wave (CDW) ground state. As expected for a highly one-dimensional conductor the exact transition temperature depends on three-dimensional coupling effects and therefore on the size of the counterion X^? = PF, AsF, SbF. Above the Peierls transition σ_| (T) can be described quantitatively within a model of CDW fluctuations leading to a pseudo gap in the electronic density of states. Below, the existence of a real energy gap at the Fermi level with a BCS-like temperature dependence determines the charge transport over more than eight orders of magnitude in the electrical resistance. For the intrinsic energy gaps 2 Δ (0), which characterize the ground state of the Peierls semiconductor, values of 120-180 meV have been found for different crystals.     

Response of finite many-electron systems beyond the time-dependent local density approximation: Application to small metal clusters

A linear response formalism is developed which is based on density functional theory within the local density approximation, but which is now corrected for its spurious self-interaction errors, in the way originally proposed by Perdew and Zunger for ground state calculations. The original formulation is extended to incorporate self-interaction corrections in the scrrening terms. The general formalism is then applied to the calculation of the static and dynamic response of the metal clusters {Na₈, Na₉⁺}, {Na₂₀, Na} and {Na₄₀ Na} within the jellium model. Comparison with experimental data and with other theoretical calculations indicates that the present formalism accounts for the overall (and most of the fine) features of the photoabsorption spectrum of these systems, providing a systematic improvement with respect to previous approaches. The remaining discrepancies are rationalized in terms of the effects to be expected by correctly accounting for the discrete structure of the ionic cores.     

Raman spectroscopy of ionic liquids derived from 1‐n‐butyl‐3‐methylimidazolium chloride and niobium chloride or zinc chloride mixtures

Anionic species formed in mixtures of 1‐n‐butyl‐3‐methylimidazolium chloride (BMICl) with different amounts of niobium pentachloride (NbCl₅) or zinc dichloride (ZnCl₂) were investigated by Raman spectroscopy. In the BMICl and NbCl₅ ionic mixtures the presence of the anion NbCl₆⁻ was detected for all compositions (molar fraction, X) and a mixture of this anion and the neutral Nb₂Cl₁₀ in acid ones. Two different anions were observed for basic mixtures of BMICl and ZnCl₂: ZnCl₄²⁻(0 < X < 0.35) and Zn₂Cl₆²⁻(X > 0.3), whereas for acidic ones three species were detected: Zn₂Cl₆²⁻(X < 0.7), Zn₃Cl₈²⁻(X > 0.7) and Zn₄Cl₁₀²⁻(X > 0.7). It has also been observed that in both cases, the formation of larger anions causes a shift of the C H stretching modes to higher wavenumbers as the result of a decrease in the hydrogen bond between Cl and the hydrogens from the cation. Copyright © 2008 John Wiley & Sons, Ltd.     

Li (i = 1, 2, 3) sub‐shell fluorescence yields for 79Au, 80Hg and 81Tl

The L _i (i = 1, 2, 3) sub‐shell x‐ray fluorescence yields (ω _i ) for ₇₉Au, ₈₀Hg and ₈₁Tl were deduced from the measured cross‐sections for the L _i (i = 1, 2, 3) sub‐shell x‐rays following ionization by 59.54 keV γ‐rays (B < E_inc < B_K) and for the L₃ sub‐shell x‐rays following ionization by Rb K x‐rays (B < E_Kα < B, B < E_Kβ < B_K), where B is the K shell/L _i sub‐shell ionization threshold of the target element. An energy‐dispersive x‐ray fluorescence setup, involving photon sources consisting of a ²⁴¹Am annular source in the direct and secondary excitation modes along with RbCl secondary exciter and an Si(Li) detector, was used for the measurements. The measured ω₂ and ω₃ values exhibit good agreement with those based on the relativistic Dirac–Hartree–Slater (RDHS) calculations, while the ω₁ values are found to be higher by ～25%. The present data indicate that the L₁–L₃ Coster–Kronig yield f₁₃ based on the RDHS calculations are overestimated. Copyright © 2004 John Wiley & Sons, Ltd.     

On a simple formula for the energy of the lowest octupole state

A recently introduced way of parameterizing the energies of 3 states in many even-even nuclei, based on the microscopic structure of the low-energy octupole mode, is slightly modified so it now includes all (non-doubly magic) nuclei with A ? 30.     

Die Super-Eich-Symmetrie in der Allgemeinen Relativitätstheorie (Einsteins A-Gruppe)

On Super-gauge-symmetry in General Relativity (Einstein's A Transformations) The super-gauge-invariance of general-relativistic field theories is given by Einstein's A-group of the transformations of the affine connections Γ which preserve the absolute parallelism. This invariance principle means that all informations about world geometry come from astronomical observations. However, the postulate of the invariance under these A-transformations implies strong conditions for microscopical structure of matter which may be interpreted as “super-gravity”.     

Anregungswahrscheinlichkeiten Probleme der Makrokausalität und Teilchendichte in der relativistischen Wellenmechanik. III

We discuss in relativistic quantum mechanics the excitation of atoms by photons, assuming an electromagnetic interaction of the form A. It turns out, that when localized in a region V at a certain time x⁰ a photon would excite atoms also outside the light-cone of V. We arrive thus at a contradiction between quantum mechanics and special relativity.     

Nachweis von radikalischen Zersetzungsprodukten in CCl4-Entladungen mit der EPR-Spektroskopie

Among the dissociation products of a r.f. discharge in CCl₄-vapour the radicals CCl₃ and Cl₂- have been identified by EPR-spectroscopy after condensation at 80 K. The gas-phase reaction CCl₃ + O₂ → CCl₃OO has been used to estimate the CCl₃ concentration to be approximately 5 · 10¹³ radicals/cm³ at p = 55 Pa. The life-time of CCl₃-radicals is governed by the rate of desactivation of some exited species (eg. CCl₄*) via . At a pressure p = 55 Pa a half-life of CCl₃-radicals of τ1/2 = 80 ms has been found.     

NOETHER'S Theorem and Higher Conservation Laws in Ultrashort Pulse Propagation

LAMB has constructed a number of local conservation laws for the differential equation σ_τ = sin σ describing ultrashort pulse propagation in a resonant medium. On the other hand it is known that from any solution of this equation others may be found by BÄCKLUND transformation. In this paper we introduce extended BÄCKLUND transformations B_a and compose them to form infinitesimal invariance transformations B_a+ε B from which via NOETHER'S theorem a system of conservation laws follows. Some of them are recognized as LAMB'S conservation laws. Another conservation law results from a scale invariance called LIE'S transformation.