bluuebunny/crossref_metadata_2025 huggingface dataset:
Eine gruppentheoretische Methode zur Berechnung von Skalarprodukten zwischen HFB-Zuständen / A Group Theoretical Method for Calculating Overlaps of HFB States
Authors: Becker Heinz Günter
Published: February 2015

Overlaps of Hartree-Fock-Bogoljubov states occurring in modified HFB theories (e. g. projected HFB) are calculated using group theoretical methods. For this purpose the Bogoliubov-Valatin transformation is generalized. The resulting nonunitary transformation leaves the Fermi commutation relations invariant, but the characteristic property of the creation and annihilation operators, namely that they are hermitean conjugate to each other, is lost. A suitable factorization of the new transformation is derived, which also applies to the unitary Bogoliubov-Valatin transformation but the structure of which is completely different from the well-known Bloch-Messiah decomposition. Furthermore, the relation between various representations of the HFB state vector is clarified.
Applications d'une representation de la mecanique quantique par des fonctions sur l'espace de phase
Authors: Huguenin P.
Published: February 2015

The Weyl-Wigner transformation enables us to construct a representation of quantum motion equations using functions in phase space. The states of the system are determined by the quasiprobability distribution in phase space and the motion is described by an orthogonal integral operator. This formalism is employed in the study of the classical meaning of the discrete symmetry groups, in the problem of defining the current probability and in the proving of the expression of cross section from the S-matrix.
Turbulent Diffusion
Authors: Graff Piiter
Published: February 2015

The problem of turbulent diffusion is re-examined. Its close connection with Schwinger's formulation of quantum field theory is established. For the transition probabilities we find a Dyson equation by using Zwanzig formalism with renormalization. The first nontrivial approximation of the memory kernel yields Saffman's result.
Strukturmodell der Metallschmelze / Structural Model of Metal Melts
Authors: Richter H. , Breitling G.
Published: February 2015

The simple primitive rhombohedron with r1 as the shortest atomic distance of the close packing of spheres (structure I) and the square with the side r1′<r1 (structure II) are experimentally suggested to be the structural elements of metal melts. In the melts with metallic binding in the lattice the rhombohedron chain I shows up as a zigzag chain with the distances , r1, r1√3, r1√7, r1√12, r1√19, and so on in the atomic distribution curve, in the melts with homeopolar binding, however, the rhombohedron chain II appears as a straight chain with the distances rν= ν·r1. In both cases the square chains I and II of structure II yield straight chains with the distances r1′ and 2 r1′ as also rν′ = v·r1′. A schematic representation gives a rapid survey of the structure of monoatomic metal melts.
Renormalized Viscosity for High Acoustic Flux in Piezoelectric Semiconductors
Authors: Wonneberger W. , Wettling W.
Published: February 2015

A renormalization procedure is described which gives the correction Δη to the crystal viscosity η when high intensity acoustic flux propagates in a piezoelectric semiconductor. Δη is attributed to the additional loss which a sound wave suffers from its production of forced higher harmonics via the electron gas. In the multimode case, the theory is based on the concept of "mode dressing". Numerical results are given for Δη/η for an Akhieser type of small signal lattice loss and for conditions found in acoustoelectric domains. It was found that Δη can exceed η appreciably when the frequency of the acoustic flux is one order of magnitude below the frequency of maximum linear electronic gain. The results are applied to the anomalous fast decay of low frequency phonons in high flux acoustoelectric domains.
Zur Dreistrahlinterferenz von Röntgen-Strahlen
Authors: Uebach W.
Published: February 2015

The eigenvalue problem of the Ewald-v. Laue dynamical theory of X-ray diffraction by perfect absorbing crystals has been solved in the case of simultaneous diffraction of CuKα-radiation by the (lll) and (l̅ll) planes of Germanium. The calculated intensities of the three beams agree fairly well with those measured on platelets of different thickness.
Notizen: Investigations on the C2H2-O2 Chemical Laser
Authors: Büger P. A. , Sadie F. G. , Malan . G.
Published: February 2015

Side light investigations of the flame in the laser cavity resulting from the oxidation of acetylene showed the presence of H2O in this system. Stimulated emission in the fundamental band of CO is partially absorbed by the water formed in the reaction. This explains the very low total output of the C2H2-O2 chemical laser.
Neutron Spin-Flip in the Reaction 12C(n,n′)12C*(4.44MeV) at 15.0 MeV
Authors: Thumm M. , Mertens G. , Mack G.
Published: February 2015

The spin-flip probability S(θ) in the inelastic scattering of unpolarized 15.0-MeV neutrons to the first 2+ state in 12C has been determined at θ = 140° (lab.) by measuring the scattered neutrons in coincidence with the subsequent 4.44- MeV deexcitation γ-rays emitted normal to the scattering plane. Time-of-flight technique with carbon recoil detection in a plastic scintillator has been used. The neutron spin-flip probability is S = 0.21±0.06.
The (Li, Ag, Na)NO3 and (Li, Ag, K )N 03 Ternary Systems
Authors: Lobbia Giancarlo Gioia , Cingolani Augusto
Published: February 2015

Sold-liquid equilibria were studied by a visual method in order to draw the polythermal projections of the (Li, Ag, Na) NO3 and (Li, Ag. K) NO3 ternary systems. The five pertinent binaries are also discussed and data concerning the characteristic points and crystallization regions are given.
On the Determination of Electron Temperature in Diffusion-Dominated Non-L.T.E. Plasmas
Authors: Drawin H. W. , Emard F.
Published: February 2015

Population densities of atomic hydrogen levels have been calculated for homogeneous stationary and diffusion-dominated stationary plasmas. The results show strong overpopulation of the lower lying excited states when the actual number density of ground state atoms is larger than the density obtained for the homogeneous stationary state. At low electron and high ground state densities the so-called Boltzmann slope is not further a characteristic quantity for the determination of electron temperatures, since the slope constant changes with quantum number. - The partial L.T.E. condition for diffusion-dominated plasmas is reexamined.
Interferometrische Messung der thermischen Zustandsgrößen von Edelgasstoßwellenplasmen1 / Interferometric Measurement of Thermodynamic Variables of Rare Gas Plasmas Produced by Shock Waves
Authors: Meiners D. , Weiss C. O.
Published: February 2015

The variation of electron density and neutral atom density behind incident shock waves in argon, krypton, and xenon are measured using a two wavelength laser interferometer with photoelectric detection of fringe shifts. The accuracy of the measured area densities ∫ Ne dl and ∫ Na dl is better than 1 per cent. Densities measured at the moment of maximum electron density agree well with Rankine-Hugoniot densities. There are no indications to deviations from LTE. Additionally, in the radiation cooling region the decrease of temperature is determined.
Effektive Elektronenzahlen in Dispersionspotentialen. Oberflächenspannung assoziationsfreier Flüssigkeiten. Diamagnetismus / Effective Electron Numbers in dispersion potentials. Surface tension of nonassociated liquids. Diamagnetism
Authors: Ulbrich Raimund
Published: February 2015

Effective electron numbers are proposed for the evaluation of the dispersion forces potentials between polyatomic molecules. Using these potentials improved formulas are derived for the calculation of the surface tension of nonassociated fluids in terms of molar volume and molecular refraction (polarizability). - Critical comments are made on certain connections between polarizability and diamagnetic susceptibility supposed in the literature.
Thermolumineszenz von kubischem und hexagonalem ZnS/Cu / Thermoluminescence of Cubic and Hexagonal ZnS/Cu
Authors: Grasser R.
Published: February 2015

The emission spectra, thermoluminescence glow curves and thermoluminescence spectra of cubic and hexagonal ZnS/(10-4)Cu phosphors were measured comparated to these of ZnS/ (5·10-4) Cu phosphors by excitation with light. The shape of the glow curves is correlated with the crystal structure of the materials.
Massenspektrometrische Untersuchungen über die neutralen Teilchen im negativen Glimmlicht einer zylindrischen Hohlkathoden-Entladung in N2 / Mass spectrometric study of the neutral particles in the negative glow of a cylindrical hollow cathode discharge in N2
Authors: Märk Tilmann D.
Published: February 2015

Detailed studies have been made of the number densities of the neutral constituents of the negative glow of a hollow cathode discharge (with currents up to 120 mA) produced in N2 at various pressures (0.2 <C p0 < 2.0 Torr).

The dissociation degree XN of N2 in the presence of the discharge was determined as a function of gas pressure p0 and discharge current Id and from these data an empirical expression was derived XN p0 = C Id , with C = 7.6·1014 particles cm-3
·A-1. Using this result a value of the density [es] of the fast electrons present in the negative glow as a function of discharge current was calculated to [es] = 5.9·107 Id. Also an estimated reaction rate constant was obtained for the fast bimolecular process N + NO→N2+0 (3.3·10-11 cm3s-1).

Relative ionization efficiency curves at mass 28 and mass 14 in the presence and absence of the discharge yielded values of the ionization and appearance potential for N2+e→N2
++2e (15.55 ± 0.1 eV), N2+e→N++N+2e (23.65±0.2 eV) and N+e→N++2e (14.35 ± 0.4 eV).
Ein Beitrag zur Analyse der Torsionsfeinstruktur Rotationsspektren von Molekiilen mit zwei Methylgruppen / A Contribution to the Analysis of Rotational Spectra of Two-Top Molecules
Authors: Dreizier H. , Legell H.
Published: February 2015

The validity of the Hamiltonian usually used for the analysis of the torsional fine structure in rotational spectra of two-top molecules with the invariance group C3v
-⊗C3v
+ has been checked. The numerical treatment of the Hamiltonian matrix by Van Vleck transformation gives nearly the same result as the direct diagonalisation used in this work. For each torsional state a different set of rotational constants should be used to reproduce the torsional multiplet splittings. The spacing between the multiplets is not given. This fact, illustrated by dimethylsilane (CH3)2SiH2 as an example, demonstrates the limitation in the validity of the Hamiltonian.
High Resolution Nonreciprocal Microwave Interferometry of Moving Media and Structures
Authors: Gehre O. , Mayer H. M. , Tutter M.
Published: February 2015

Three experiments are described in which the relative motion of media or structures causes nonreciprocal effects of first order in ν/c. The first two experiments deal respectively with the Fresnel effect due to the motion of a normal dielectric and the electron drift in the plasma of a glow discharge. The third experiment is a microwave analogon to the historical experiments of Harress, Pogany and Sagnac. To our knowledge these are the first investigations of the well-known effects under conditions where the transverse dimensions of the waves are comparable to the wave length. Under such conditions the nonreciprocal effects when expressed in fringe shifts (or phase angle) remain small. They could, however, be detected after the development of an elaborate microwave interferometry which could resolve fringe shifts down to the order of 10-6.
Zur näherungsweisen Berechnung der elektrischen Leitfähigkeit eines Plasmas
Authors: Schirmer H. , Stober I.
Published: February 2015

In order to calculate the electrical conductivity of a plasma an approximate formula has been derived which is based on an improvement of the expression corresponding to a Lorentzian gas. The deviation from the exact solution (which is based on the Boltzmann equation of a plasma) is in most cases lower than 5% and will exceed this deviation only in exceptional cases.

The calculations have been performed for xenon and neon.
Einflufi des Lösungsmittels auf die thermodynamischen Parameter des excimeren αNPO / Solvent Effect of the Thermodynamic Properties of αNPO Excime
Authors: Polacka B. , Szymkowiak H.
Published: February 2015

The thermodynamic properties of excimer formation process of αNPO in dioxane, methyl methacrylate, toluene, ethyl ether, acetone and acetonitrile have been determined. It has been found that the changes of entropy and enthalpy in the excimer formation process are smaller in all polar solvents than in nonpolar solvents. This effect can be explained by the influence of dielectric constant of solvent on the excimer stability of αNPO.
Kinetic Theory of Nonequilibrium Alignment Phenomena in Atomic Vapors
Authors: Köhler W. E. , Hess S.
Published: February 2015

Nonequilibrium alignment phenomena in gases of polyatomic molecules (Senftleben-Beenakker effect, flow birefringence) have been studied extensively during the last decade. Similar effects should also exist for atoms with nonzero electronic orbital angular momentum. The Waldmann- Snider equation (considered as Boltzmann equation for reacting mixtures) is used to derive an expression for the tensor polarization caused by a flow field in such atomic vapors. As a simple special case 2P-atoms are treated as an effective two level system (fine structure doublet). They can be tensor-polarized in the state with j = 3/2. An ansatz is made for the nonspherical interaction potential between 2P-atoms. The scattering amplitude is calculated in first order Born approximation which is reasonable for the high temperatures necessary. The relevant cross sections and collision integrals are evaluated. The temperature dependence of the alignment and its order of magnitude are discussed. Although the effect is rather small it should be detectable by optical methods (flow birefringence). The connection of flow birefringence and collisional alignment is elucidated.
Low-lying Levels in Odd-mass Au Nuclei
Authors: Bashandy E. , El-Nesr M. S. , Mousa M. G.
Published: February 2015

The low energy levels of 197Au and 199Au have been investigated by means of a high resolution double focusing beta-ray spectrometer. The conversion electron ratios as well as the K-conversion coefficients of low-lying transitions were determined. The K-internal conversion coefficients of the 191 keV transition in 197Au indicated no EO contribution. The level structure of the lower excited states in 197Au and 199Au are discussed in terms of existing nuclear models.
Collisional Transfer of Energy in Ammonia; Some Triple Resonance Experiments
Authors: Jones Harold , Eyer Achim
Published: February 2015

Infrared-microwave-microwave triple resonance experiments in ammonia are reported. The power modulated P13 line of a N2O laser was used to pump the ν2[Q(8,7)] transition of ammonia. The dependance of the intensity of the collisionally induced signals produced at the (7,7), (6,6), (5,5) and (4,4) microwave transitions on c. w. microwave power applied to the (8,7) transition was measured. From the null signal observed for the (7,7) transition when the (8,7) transition was saturated, it was concluded that population changes produced in the (7,7) levels occur predominently via direct collisional transitions which are strongly parity sensitive and that other processes have little contribution. The signals observed for the (6,6), (5,5) and (4,4) are produced by processes which are largely insensitive to parity.
Ein Prozeßrechner-gesteuertes Mikrowellen-Stark-Spektrometer hoher Nachweisempfindlichkeit / A Computer Controlled Microvoave-Stark-Spectrometer with High Sensitivity
Authors: Zeil W. , Gegenheimer R. , Haas B. , Peting K. H.
Published: February 2015

A computer-controlled microwave-Stark-spectrometer is described. By setting the frequency step by step with following data correction it is possible to use the method of time averaging. It results a high sensitivity. Microwave lines with an absorption coefficient 3.3 · 10-10 and 1.4 · 10-10 cm-1 have been detected and their frequencies measured with high accuracy.
Notizen: Zur Deutung der unterschiedlichen Strahlen- Empfindlichkeit organischer Moleküle / On the Radiation Sensitivity of Organic Molecules
Authors: Spehr R. , Schnabl H.
Published: February 2015

If an electron initially was localized at one carbon atom of a benzene molecule, its probability density will quickly dissipate over the whole ring. A rough model calculation using Wannier functions yields T1/2 ≳ 10-16 sec for the decay of the original distribution. A similar spreading will happen to a defect electron produced locally at the bond between two atoms. This effect of “healing” should be taken into consideration when the mechanism of radiation damage in organic molecules is discussed.
Electronegativities and Gaussian Orbital Exponents
Authors: Szöke S. , Preuß H.
Published: February 2015

A method for selecting orbital exponents for Gaussian type functions (αg’s) may be based on a connection between these exponents and Pauling electronegativities (ε’s). An analogous relationship between αg’s and ε’s would be expected: GTO exponents derived by different authors give αg/ε2’s which are approximately constants. A number of GTO sets recommended by several authors have been revised.
On the Correlation Factor for Diffusion in the f.c.c- and NaCl-Structure
Authors: Abels A. E. P. M. , Bakker H.
Published: February 2015

The correlation factor for impurity diffusion in the f.c.c.-structure by means of a vacancy mechanism is calculated as a function of nine distinct vacancy-atom exchange rates.

Furthermore an expression is derived for the correlation factor for diffusion of aliovalent impurities in the NaCl-structure including an electrostatic impurity-vacancy interaction.
Molar Volumes in Molten NaBr, RbBr, NaBr-TlBr and RbBr-TlBr
Authors: Buckle E. R. , Tsaoussoglou P. E.
Published: February 2015

Densities in molten NaBr and RbBr and molar volumes in their binary mixtures with TlBr are reported. The pyknometric method again gave slightly higher densities (0.1 - 0.2%) than previous Archimedean methods. In the mixtures the excess volume is no greater than ±1% but its variation with composition and temperature broadly resembles that in the MX-TIX systems reported previously. A relationship is apparent between the overall trend in the molar volume with composition and temperature and the variation in the Tl-X overlap by nmr. Together with the stoichiometry, this suggests that in the region of strong negative deviation coordination is high and localized orbital overlap low between cations and anions.
Die Molekülstruktur des Trifluorsilylphosphans (F3SiPH2) / Molecular Structure of Trifluorosilylphosphane (F3SiPH2)
Authors: Demuth R. , Oberhammer H.
Published: February 2015

The molecular structure of trifluorosilylphosphane in the gas phase has been determined by electron diffraction. A short P -Si bond distance of 2.207 (3) Å as compared to other investigated silysphosphanes was found for this molecule. The other structural parameters and mean square amplitudes are given in the article.
Zum äußeren Schweratom-Effekt der Phosphoreszenz in nicht-fluoreszierenden aromatischen Verbindungen / The External Heavy-Atom-Effect of Phosphorescence in Non-fluorescing Aromatic Compounds
Authors: Zander M.
Published: February 2015

Phosphorescence quantum yields of six non-fluorescing naphthalene derivatives have been measured in ethanol and ethanol-ethylbromide 1:1 at 77 °K. The observed enhancement of phosphorescence yield of four of these in the heavy atom solvent is explained with the assumption that the rate of the phosphorescence transition is increased relatively to the radiationless desactivation of the triplet state.
I.R. Optical Absorption of Antimony Films
Authors: Abou El Ela A. H. , Mahmoud S.
Published: February 2015

Measurements of the optical constants give information about the electronic structure of antimony. Quantum transitions between the energy bands play a significant role in I.R. absorption. The width of the energy gap can be obtained from such measurements.
Search for a Primary Isotopic Effect on the Magnetic Shielding of the Rubidium and Cadmium Isotopes
Authors: Krüger H. , Lutz O. , Nolle A. , Schwenk A. , Stricker G.
Published: February 2015

The ratios of the gI-factors of 85Rb and 87Rb and of 111Cd and 113Cd have been measured in aqueous solutions of salts by the NMR method with high accuracy. A comparison with the same ratios measured by optical pumping techniques in free atoms shows agreement within the limits of error of 2.3 · 10-6 in the case of rubidium and of 3 · 10-7 in the case of cadmium: No difference in the magnetic shielding between the isotopes is observable.
Berichte:Some Topicsinthe Theory and Applications of the Optical Model
Authors: Bertero M. , Passatore G.
Published: February 2015

In some recent works a dispersion relation proposed by Feshbach for the generalized optical potential has been used in order to analyse the energy dependence of the strength of the empirical optical potential. In the first part of this report the mathematical problems arising in the derivation of the dispersion relation and the results obtained in this direction are discussed; in the second part the approximations introduced in the application of the dispersion relation are analysed and the results concerning the non-locality of the generalized optical potential are reviewed.
Lowest Approximation of Relativistic Nucleon-Nucleon Scattering in Functional Quantum Theory
Authors: Illig K.
Published: February 2015

Using a selfcoupled spinorfield (Fermicoupling) as a model to describe relativistic nucleon-nucleon scattering it is shown that the functional S -matrix construction for relativistic clusters in nonlinear spinortheory proposed by Stumpf reproduces in lowest order perturbation theory the result obtained by usual quantum field theoretical methods.
Ligand Field-Spin Orbit Energy Levels in the d4 and d6 Electron Configurations of Octahedral and Tetrahedral Symmetry
Authors: König E. , Kremer S.
Published: February 2015

The complete ligand field -Coulomb repulsion -spin orbit interaction matrices have been derived for the d4 and d6 electron configurations within octahedral (Oh) and tetrahedral (Td) symmetry. The calculations were perform ed in both the weak-field and strong-field coupling schemes and complete agreement of the results was achieved. The energy matrices are parametrically dependent on ligand field (Dq), Coulomb repulsion (B, C) and spin-orbit interaction (ζ). Correct energy diagrams are presentend which display the splittings by spin-orbit perturbation as well as the effect of configuration mixing. Applications to the interpretation of optical spectral data, to the detailed behavior at the crossover of ground terms, and to complete studies in magnetism are pointed out.
Die Medienabhängigkeit der spektralen Lage der Fluoreszenzbande von Indol und substituierten Indolen / The Influence of Environment on the Fluorescence Spectra of Indole and Substituted Indoles
Authors: Kawski A. , Czajko J.
Published: February 2015

To gain information about the nature of the microenvironment of tryptophane residues in proteins, the absorption and fluorescence spectra of such model compounds as indole,- 1,2-dimethylindole, and 2-phenylindole were examined in n-heptane -n-butanol mixtures at different temperatures (20, 80 and 120 °C ). Anomalously large red shifts in the fluorescence bands of these compounds at different n-butanol concentrations in n-heptane indicate that the added n-butanol molecules are concentrated around the solute molecules by electrostatic interactions. The red shift is due to the marked increase in the dipole moment of the excited state and to the number of n-butanol molecules in the solvent shell which can reorient themselves during the lifetime of the excited state of the solute molecule. From the spectroscopic data, making use of the “solvent-shift” theory and the statistical model of Mazurenko, the effective dielectric constant of the microenvironment, the average degree of filling up the solvent shell with n-butanol molecules, the average coordination number and the average interaction energy of the solute with the solvent molecules in the ground and excited state, were calculated.
Centrifugal Distortion Constants in 1.3 Propiolactone
Authors: Boggia Luis Mario , Filgueira Roberto Raul , Sorarrain Oscar Manuel , Damiani Damiano
Published: February 2015

The centrifugal distortion constants for

were calculated using Dowling and Watson’s formalisms. From the fitting analysis and the deviation of predicted transitions it is concluded that the second formalism must be adopted. For the different parameters we have: A′ = 12406.012 ± 0.005 MHz; B′ = 5244.456 ± 0.002 MHz; C′ = 3869.191 ± 0.002 MHz; dJ = - 2.08 ± 0 .05 kHz; d J K = -23.63 ± 0.95 kHz; d K = - 33.43 ± 1.69 kHz; d W J = (0.56 ± 0.01) X 10-6; d WK = (5.08 ± 0.22) X 10-6.
High Precision Method for Determining Twist Elastic Constants of Nematic Liquid Crystals I. Theory
Authors: Dreher R.
Published: February 2015

In a magnetic field a nematic liquid crystal may sustain a variety of twist modes. Their influence upon light propagating trough the liquid crystal can be used to evaluate the twist elastic constant from simple reflection or transmission measurements.
Experimental Proof for Electrochemical Non-Equilibrium Saturation Currents in Organic Crystals
Authors: Willig F.
Published: February 2015

For the same redox ion, diffusion controlled currents have been compared which were obtained at organic crystals and at a gold electrode. These experiments yield quantitative proof for electrochemical saturation currents in organic crystals with electrolytic contacts. Essential for this result is a modified voltage step method which enables an application of a high voltage simultaneous with the first contact between the crystal surface and the charge injecting electrolyte. The conditions necessary for the occurrence of a saturation current are discussed which also determine the electrochemical nature of this current corresponding to an ideal non-equilibrium between redox system and organic crystal.
Kinetics of the Reaction Between S2O3
-- and I3
- in Aqueous Solution
Authors: Rao T. S. , Mali S. I.
Published: February 2015

The kinetics of the reaction between

has been studied under conditions of production of iodine at a known rate by the persulfate-iodide reaction and its consumption by S2O3
-- . The effective concentration of iodine during the steady state is measured from its reduction potential at a bright platinum foil electrode. The reaction is of first order with respect to I3
- and S2O3
-- individually and hence of over all second order. The specific rate is 1.51 X 105 M -1 sec-1 and the frequency factor is 1.69 × 1012 M -1 sec-1 at 25 °C. The energy of activation for the reaction is 9.58 × 103 cal/mole and the entropy of activation is -2.55 cal/mole deg.
A New Electron Microscope Imaging Method for Enhancing Detail in Thin Biological Specimens
Authors: Unwin P. N. T.
Published: February 2015

An electron microscope imaging method is described which makes use of an electrostatic device, analogous in function to the absorbing phase plate of light microscope, to produce strong contrast in biological specimens. This device is situated at the back focal plane of the objective lens in place of a normal objective aperture. The images created provide an especially realistic representation of the specimen structure and contain information about it that would not necessarily be able to be detected by the conventional bright field method of observation.
Microwave Spectrum of Ethyl Cyanide; r0-Structure, Nitrogen Quadrupole Coupling Constants and Rotation-Torsion-Vibration Interaction
Authors: Mäder H. , Heise H. M. , Dreizler H.
Published: February 2015

An investigation of the microwave spectra of ethyl cyanide CH3CH2CN and the isotopes CH2DCH2CN, CH3CD2CN was carried out. The ground vibrational state of CH3CH2CN was reexamined under high resolution to give three centrifugal distortion constants DJ , DJK and DK. From the rotational constants of the ground vibrational state of CH3CH2CN, CH3CD2CN, CH2DCH2CN (symmetric) and CH2DCH2CN (asymmetric), CH3CH2
13CN and CD3CHDCN a r0-structure is derived. For the isotopes CH3CD2CN, CH2DCH2CN (symmetric) and CH2DCH2CN (asymmetric) the diagonal elements Χaa , Χbb and Χcc of the quadrupole tensor with respect to the principal axes of inertia were deduced from the hyperfine structure of the rotational lines. The off-diagonal element Χab for CH3CD2CN and CH2DCH2CN (symmetric) and the principal elements Χzz , Χxx of the quadrupole coupling tensor were obtained from Χaa, Χbb of the two molecules and from the principal axis rotation angle about the c-axis produced by isotopic substitution. For the analysis of the rotational spectra in the first excited states of methyl torsion and the lowest frequency in plane bending vibration of normal ethyl cyanide a molecular model with two internal degrees of freedom is considered. From the rotational line splittings in both states the coefficients V3 and V6 of the Fourier expansion of the potential hindering the internal rotation of the methyl group are determined.
Peculiarities of the Helium-Beam Scattering on Metal Surfaces
Authors: Comsa George , Comsa Gerda H. , Fremerey J. K.
Published: February 2015

Some of the peculiarities of the atom scattering on metal surfaces are discussed in connection with the applicability of the Debye-Waller factor (DWF). The influence of the attractive potential well and of the finite size of the incident particles upon the scattering is commented. By comparing calculated DWF-values with experimental He scattering data it is concluded that the existence of diffraction is a necessary but not a sufficient condition for the applicability of the DWF. It is finally shown that the smooth potential surfaces which characterize the interaction between atoms and metal surfaces explain the apparently reduced thermal roughening observed experimentally.
Energy Exchange between H D (B1 Σu
+, υ′, J′ ) and Ground State H2 and D2 by Interaction of Electronic Transition Dipole Moments
Authors: Fink E. H. , Hafner P. , Becker K. H.
Published: February 2015

Steady state fluorescence experiments with mixtures of HD and H2 or D2 have given effective cross sections for energy exchange processes in collisions of electronically excited HD and ground state H2 and D2 molecules in well defined quantum states. The experimental results are compared with first order calculations using the Sharma-Brau theory of energy transfer due to the interaction of transition dipole moments.
Messung absoluter Quantenausbeuten von Quantenwandlern / Absolute Quantum Yield Measurement for Quantum Counters
Authors: Küttner H. G. , Selzle H. L. , Schlag E. W.
Published: February 2015

The absolute quantum yield of different fluorescing dyes has been measured in the solid micro crystalline phase, with a view towards finding dyes which exhibit a constant quantum yield in the visible spectrum. Some suitable dyes have been found and these can now be used as quantum counters for the absolute measurement of photon flux, such as in photochemical experiments. The specific characteristic of the dye responsible for this effect appears to be connected with the action of hydrogen bonds as energy transfer agents.
Field Induced Ion Molecule Reactions in Adsorbed Layers Studied by Pulsed Field Desorption
Authors: Röllgen F. W. , Beckey H. D.
Published: February 2015

The formation of ions under field ionization conditions is partly due to ion molecule reactions in adsorbed layers on the emitter surface. In order to study these reactions a pulsed field desorption (PFD) technique was applied, by which ions resulting from these reactions are detected with high relative intensity. The PFD-mass spectra of some small organic molecules are discussed with respect to the principal reaction mechanisms and types of ions formed.

It was found that if reactions involving chemical interaction with the surface are left out of consideration only proton transfer reactions are the primary processes. Desorption products resulting from proton transfer reactions are, for example, (M+H)+, (2M+H)+, (3M+H)+, (M+CH3)+ and (2M)+ ions in the case of methanol. The formation of complexes preceeding atom rearrangement reactions are suppressed by the high electric field and consequently could not be detected. Secondary reactions of the (M-H)•-radical lead to the elimination of H- from molecules and in certain cases to the formation of addition complexes.

Field induced reactions were found to occur almost adiabatically, i.e. it is not necessary to supply the ionization potential of the proton donor in a proton transfer reaction. Products of reactions with ionization energies above the ionization potential of the molecules involved in the reaction are not observable. To a first approximation the electron transition probability for field reactions seems to be dependent on the energy of formation of the ions and not on the type of reaction.
Bestimmung von Streuquerschnitten für thermische Elektronen aus der Linienform von ECR-Signalen / Determination of the Scattering Cross Section for Thermal Electrons from the Line Shape of ECR-Signals
Authors: Schultes E. , Schumacher R. , Schindler R. N.
Published: February 2015

Changes of line width and line shape of electron cyclotron resonance (ecr) signals are measured as function of the pressure of neutral gases. The results are discussed in terms of an analysis for the absorption of microwave power by electrons given by Fehsenfeld et al. Good agreement is found for σ-values as obtained in ecr and drift tube measurements.
Senftleben-Beenakker Effects, Nonresonant Absorption and Collision Integrals for Gases Consisting of Symmetrie Top Molecules
Authors: Moraal H.
Published: February 2015

The kinetic theories of the electric and magnetic Senftleben-Beenakker effects and of nonresonant absorption in polar symmetric top gases are reviewed, using an expansion of the distribution function-density matrix which includes the dipole moment operator μe . General expressions are given for the elastic parts of all collision integrals coupling two purely angular momentum dependent tensors. This is done for a variety of nonspherical potentials, including the dipole-dipole (DD), dipole-quadrupole (DQ) and quadrupole-quadrupole (QQ) interactions. Model calculations for the m ethyl halogenides are performed for these potentials for a number of collision integrals, namely the nonresonant cross section and three collision cross sections which are of importance for the shear viscosity Senftleben-Beenakker effects. These calculations indicate that DD, DQ and QQ interactions may all be important, that at least half of the nonresonant cross section is elastic and that the average cross section extracted by means of Levi’s theory from electric field shear viscosity Senftleben-Beenakker measurements is approximately equal to the reorientation cross section for the tensor polarization [μe](2).
Metastabile Deformationen in nematischen flüssigen Kristallen / Metastable Deformations in Nematic Liquid Crystals
Authors: Heppke G. , Schneider F.
Published: February 2015

The magnetic field induced elastic deformations of nematic liquid crystals are studied theoretically. In accordance with the theory of Dafermos, two types of elastic deformations are predicted which differ in energy. The properties of the metastable deformations are discussed in detail.

Experimental studies have been performed on MBBA using electrical conductivity measurements. Metastable deformations are obtained after rotating the direction of the magnetic field by more than 90° with respect to the direction of the homeotropically aligned sample. The observed conductivity values are in good agreement with theory.
Tunnelspektroskopie an dünnsten supraleitenden Aluminium-, Indium- und Bleischichten / Superconducting Tunneling into Ultrathin Aluminum, Indium and Lead Films
Authors: Sixl H. , Gromer J. , Wolf H. C.
Published: February 2015

We report about tunneling experiments on extremely thin superconductors with barriers of aluminium- oxide and in addition silicon-monoxide or naphthalene, all condensed at 4.2 °K. The tunneling spectra of aluminium, indium and lead films show a large tunneling anomaly at a film thickness just above the critical thickness for conductivity and superconductivity: in the low bias range (between 2 and 5 mV) the tunneling resistivity dU/dI is increased by about 20 to 30 per cent with respect to the corresponding resistance of thicker films. This anomaly disappears when the film thickness is increased by 30 to 40 Å. Two models are presented, which can explain the tunneling anomaly by the quantum size effect in the very thinnest films of either the phonon states or the electronic states.

The energy gaps and the transition temperatures of the superconductors show a marked dependence on the film thickness between the critical film thickness and 300 Å, dependent on both, the superconductor itself and on the substrate, naphthalene or silicon-monoxide. This dependence can be described completely by the altered electron-phonon coupling at the film surfaces and by size quantization of the electronic states.
N-Chloro-chloroformimidoyl chloride: A NQR-Study
Authors: Lötz A. , Voitländer J.
Published: February 2015

An extension of Bayer’s and Tokuhiro’s ideas on NQR temperature dependences and molecular librations to the case of polyhalogenated planar molecules results in a method for line assignment, detection of special effects, such as dynamic phenomena, and computation of the absolute values of librational frequencies by using the temperature dependence of different isotopes. This is demonstrated for the case of the title compound.
On the Normalization of Meson Eigenstates in Functional Quantum Theory of the Nonlinear Spinor Field
Authors: Englert D. , Stumpf H.
Published: February 2015

In the framework of the functional quantum theory of the nonlinear spinor field the normalization of functional eigenstates of scalar mesons is performed. By calculating the lowest approximation of the functional eigenstates for scalar mesons from the dynamical functional equation of the theory, it follows that scalar mesons of positive as well as of negative parity are admitted. Requiring a positive norm for physical particles the result of normalization shows that mesons with positive parity are excluded, while meson states with negative parity give a positive definite norm. This corresponds to experimental experience
Resonance Neutron Capture in 55Mn and Levels in 56Mn
Authors: Börner H. , Schult O. W. B.
Published: February 2015

The γ-spectrum of 56Mn from resonance neutron capture in 55Mn has been measured in the energy range 4.2 ≦ E ≦ 7.3 MeV. The 215 keV level of 56Mn was found to be populated through about 50% of the primary γ-ray intensity leading to the 212/215 keV doublet
Absorption Spectrum of As2 Further Analysis of the A→X System and Observation of New Electronic States
Authors: Sibaï Abdel Mooti , Perdigon Pierre , Topouzkhanian Ari
Published: February 2015

Within the study of the interaction between A and B states of As2 molecule, a high resolution analysis of 16 absorption bands with 11 ≦ υ ≦ 17 in the A ← X system has been performed. The following constants are proposed for the A state: T00 = 40145.9 cm-1, ωe = 262.7 cm-1, ωe xe = 0.48 cm-1, Be = 0.0797 cm-1, De ≅ 3 X 10-8 cm-1 , αe = 0.00031 cm-1 , re = 2.374 Å. Three new vibronic levels have been discovered in the 42 400 -44 500 cm-1 energy range, either directly or by the perturbations they induce in A levels
Observation et analyse vibrationnelle de nouveaux systemes de Bandes d’absorption de molecules lourdes dans l’ultraviolet lointain Cas de Sb2 et Bi2 / Observation and Vibrational Analysis of new Absorption Band Systems of Heavy Molecules in the Vacuum Ultraviolet. Case of Sb2 and Bi2
Authors: Topouzkhanian Ari , Sibaï Abdel Mooti , d'Incan Jean
Published: February 2015

86 new absorption bands of the Sb2 molecule, all degraded to longer wavelenghts, have been observed in the vacuum ultraviolet. They belong to previously known systems, particularly the G ← X system discovered recently by flash photolysis, and extend them. The 30 new bands of Bi2, located in the same region, form two new systems
Dielektrische Verluste in verdünnter Lösung und innermolekulare Dipolbeweglichkeit bei Carbinolen / Dielectric Loss of Carbinols in Dilute Solutions and Intramolecular Dipol Orientation
Authors: Hanna F. F. , Bishai A . M. , Straßmann M. , Noerpel W.
Published: February 2015

The dielectric loss of benzyl alcohol, diphenyl- and triphenylcarbinol in dilute solutions of benzene and carbon tetrachloride is measured in the microwave range from 1 to 300 GHz. The absorption curves can be separated into three regions, the one with the longest relaxation time is due to the overall rotation of the molecule. In both the carbinols the OH-group is hindered in its rotation and partly it reorients with time constants which we suggest being due to the rotation of the phenyl ring. For the fast angular oscillations (libration) of the OH-group itself time constants between 0.15 and 3 ps are extrapolated
On a General Formula for the Transition Temperature of Superconductors
Authors: Kessel W.
Published: February 2015

A method of solution of the Eliashberg equations in the theory of superconductivity is derived which uses the fact that near the transition point the energy gap is small compared to the energies over which the electron-phonon properties vary appreciably. On this basis the Eliashberg equations are converted into linear inhomogeneous integral equations. Their solution is given in operator form and provides a general formula for the transition temperature
Determination of the Hypersonic Velocities in the Molten Salts NaNO3 and KNO3
Authors: Gustafsson Silas E. , Knape H. E. Gunilla , Torell Lena M.
Published: February 2015

Hypersonic velocities in the molten salts NaNO3 and KNO3 have been obtained by Brillouin scattering measurements. A He-Cd laser, 4416 Å, was used as a radiation source and the scattered light was analyzed with a pressure-scanned Fabry-Perot spectrometer. The temperature dependence of the sound velocity was determined in a temperature range covering some 100° above the melting point of the investigated salts. The obtained hypersonic velocity for NaNO3 was about the same and for KNO3 greater than reported ultrasonic velocities indicating that the measurements are performed in a frequency region below any possible relaxation frequency for NaNO3 and above some possible relaxation frequencies for KNO3
Self-Diffusion Coefficients in the Molten AgNO3-AlkNO3 Systems
Authors: Zuca Stefania , Constantinescu Mariela
Published: February 2015

The cationic self-diffusion coefficients in the fused (Ag-Li) NO3, (Ag-Rb) NO3 and (Ag-Cs) NO3 systems have been investigated as a function of composition and temperature. The deviation from linearity of the D+ vs. composition isotherms in the (Ag-Alk) NO3 series is discussed in terms of ionic interactions. Quantitative relationships between D+ and ionic size and mass have been established
Metastable Ions as a Guide to Reaction Mechanisms. Loss of ’OH from Substituted Nitrobenzene Molecular Ions
Authors: Keough T. , Beynon J. H. , Cooks R. G. , Chang C. , Shapiro R. H.
Published: February 2015

Loss of ‘OH from the molecular ions of nitrobenzenes having various substituents in the m- and p-positions does not involve substituent randomization and reaction through the ortho-isomer; the kinetic energy release accompanying metastable ion fragmentation shows this latter to be an entirely distinct process. The origin of the hydrogen lost as 'OH in the m- and p-compounds is the ring (mainly the position ortho to the nitro group in methyl p-nitrobenzoate). However, the hydro­gens of the substituent do play a direct role in the reaction as shown by an isotope effect upon the abundances of metastable peaks. Hydrogen atom abstraction by the ionized nitro group apparently occurs independently of participation by the substituent on the nitrobenzene but a second hydrogen transfer from this substituent to the ring precedes fragmentation. Direct interaction between groups o ' the aromatic ring that are not ortho to each other therefore apparently does not occur. Inversion of the rate constants for two reactions, NO' loss and CH2O loss from the methyl p-nitrobenzoate molecular ion in the metastable ion time range, has been observed following isotopic substitution.
Trimethylsilylcyanid
Authors: Dakkouri Marwan , Oberhammer Heinz
Published: February 2015

The gas-phase molecular structure of (CH3)3SiCN was determined by means of electron diffraction. The structural parameters are found to be:

ra (Si-C≡) = 1.844±0.022 Å, ra (C ≡ N) = 1.170±0.007 Å, ra (Si - Cm) = 1.871 ± 0 .008 Å, ra (C-H ) = 1.111 ±0,009 Å, (∡ Cm- Si -C = ) = 107.0° ± 1.5 ° and (∡ Si - C - H ) = 110.4° ± 1.5°. The mole fraction of Isocyanide at 45 °C nozzle temperature was estimated to be smaller than 2%
Kristallstruktur und Konstitution des Perchlorcyclooctatetraens (y-C8Cl8) / Crystal Structure and Constitution of Perchlorocyclooctatetraene (y-C8Cl8)
Authors: Haase J. , Widmann P.
Published: February 2015

The crystal structure of perchlorocyclooctatetraene (y-C8Cl8) has been investigated and solved by direct methods. As a result of the cry stal structure analysis the constitution of the molecule, derived by Helm, Roedig, Smith and West from spectroscopic measurements, has been found to be true
Some ab Initio Calculations on Indole, Isoindole, Benzofuran, and Isobenzofuran
Authors: Koller J. , Ažman A. , Trinajstić N.
Published: February 2015

Ab initio calculations in the framework of the methodology of Pople et al. have been performed on indole, isoindole, benzofuran. and isobenzofuran. Several molecular properties (dipole moments, n. m. r. chemical shifts, stabilities, and reactivities) correlate well with calculated indices (charge densities, HOMO-LUMO separation). The calculations failed to give magnitudes of first ionization potentials, although the correct trends are reproduced, i. e. giving higher values to more stable isomers. Some of the obtained results (charge densities, dipole moments) parallel CNDO/2 values.
Polaron Conduction and Optical Absorption of Amorphous Selenium Films
Authors: Ela A. H. Abou El
Published: February 2015

The temperature dependence of electrical conductivity in amorphous selenium films is investigated. The experimental results show a polaronic conduction in the states near the Fermi level, in agreement with Mott’s model. Optical absorption measurements show the rate at which the valence band states fall off with energy into the energy gap.
Diffusionsuntersuchungen im System Cu-Ga
Authors: Wilhelm M.
Published: February 2015

For temperatures between 500 °C and 700 °C concentration profiles of diffusion layers have been investigated in couples containing copper and a copper-gallium-alloy with varying composition by means of quantitative electron-probe-microanalysis. From these profiles values have been derived for the growth constants k and the activation energies Q̅ controlling growth of the diffusion zone, and for diffusion coefficients D and activation energies Q of the chemical diffusion as well as for the intrinsic diffusivities DGa and DCu .
Einfluß der Thermodiffusion auf die chemischen Transportvorgänge in Halogenglühlampen
Authors: Neumann Gerhard M.
Published: February 2015

The influence of thermodiffusion on bulb-blackening in tubular halogen incandescent lamps has been investigated experimentally for additions of methylenebromide, bromoforme or bromophosphornitrile to argon, krypton and xenon as filling gas. A strong dependence of blackening on the kind of the filling gas has been found. The influence of thermodiffusion on chemical transport may be interpreted in terms of the thermal diffusion coefficient a, which has been calculated according to Hirschfelder. Using higher concentrations of halogen, blackening of the bulb can be prevented, independent of the nature of the filling gas.