Published by De Gruyter

Volume 36 Issue 2

Issue of Zeitschrift für Naturforschung A

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Open Access June 2, 2014

On the Inversion of the Linearized Collision Operator

Ulrich Weinert

Page range: 113-120

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Abstract

Some features are discussed in connection with the representation of the linearized Boltzmann collision operator and its inversion. It is shown that under certain assumptions the inverse operator can be given explicitly as an integral kernel function.

Open Access June 2, 2014

Strong Collision Induced Spin-Lattice Relaxation for Tunneling NH₄-ion Systems in the Rotating Frame

Kunihiko Morimoto

Page range: 121-127

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Abstract

In order to calculate the rotating frame spin-lattice relaxation time T 1 ρ for tunneling NH 4 -ion systems at low temperature, a model of relaxation, which is available when γH L τr⪢1, is proposed, where H L is the local dipolar field and τr the correlation time. The present model is useful especially in two cases: (1) when the NH 4 -ion is relatively magnetically isolated and the assumption of a common spin temperature cannot be used. (2) when the level crossing of the NH 4 -ion occurs in the rotating frame. In case (1), non-single exponential relaxation is predicted. In case (2), T 1 ρ is shown to be proportional to τr, while the prediction of the weak collision theory is T 1 ρ ∞cc τr -1 . The present model is compared with the strong collision theory of Slichter and Ailion.

Open Access June 2, 2014

Topological Resonance Energy of Very Large Benzenoid Hydrocarbons

Ivan Gutman

Page range: 128-131

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Abstract

An approximate expression is obtained for the resonance energy of benzenoid hydrocarbons. The resonance energy is shown to depend in a simple manner on the number of six-membered cycles and on the number of Kekule structural formulae of the molecule. By this approach, the resonance energies of very large benzenoid hydrocarbons can be determined.

Open Access June 2, 2014

Low-Energy e-He(2¹L) Scattering Calculations

D. Koledin, P. Grujić

Page range: 132-139

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Abstract

Cross sections for e-He(2 1 L) scattering have been calculated in the energy range 1 ≦ E ≦ 4 eV. For l > 0 partial cross sections a simple analytical method, proposed by the authors before, which is essentially an extension of Seaton's exact resonance method, has been applied. In the case l = 0, when a complex "angular momentum quantum number" in the rotated space appears, a matching procedure has been adopted, making use of a more realistic model potential. The results for Q(2 1 S-2 1 S), Q l (2 1 S-2 1 P) and Q(2 1 P-2 1 P) cross sections are compared with other theoretical calculations and in the case of the elastic Q(2 1 S-2 1 S) cross section with the available experimental data as well. The applicability of the analytical method used in the electron-atom scattering calculations is discussed, in particular for those processes which play a dominant role in the Stark broadening of spectral lines from plasmas. Finally, the relevance of the present method to searching for an eventual resonant (or virtual) state near 2 1 S threshold has been discussed.

Open Access June 2, 2014

Carbon Contaminant Buildup and Sputtering Behaviour on Zinc Oxide During XPS Examination

M. Mintas, G. W. Filby

Page range: 140-143

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Abstract

The effect of argon and oxygen sputtering on carbon contaminant buildup on ZnO during XPS (X-ray photoelectron spectroscopy) analysis has been examined. Argon and oxygen sputtering cause a rapid decline in hydroxyl oxygen and contaminant carbon content at the surface. Reduction to metallic zinc is not observed. In a carefully baked instrument after sputtering a stable clean surface could be maintained over several hours of analysis.

Open Access June 2, 2014

Three-dimensional Analytical Force-free MHD Equilibria

D. Lortz, W. Lötz, J. Nührenberg, F. Cap

Page range: 144-149

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Abstract

Three-dimensional analytical force-free magnetohydrostatic equilibria may be obtained by separation of variables with respect to cylindrical coordinates. These equilibria are then used to study numerically flux surfaces of various three-dimensional configurations.

Open Access June 2, 2014

Röntgen-Beugungsuntersuchungen an Bi-In-Schmelzen / X-Ray Diffraction Experiments with Bi-In-melts

R. Bek, E. Nold, S. Steeb

Page range: 150-153

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Abstract

Using MoK α-radiation and a θ-θ diffractometer from molten In and Bi as well as six molten Bi-In alloys (8; 22; 27; 33.3; 50; and 77 at % Bi) intensity curves were obtained at 10 °C above the liquidus temperature. The measurements were performed in the q-region up to 14.5 Å -1 . From the Fourier transform of the structure factors coordination numbers N I tot and radii r I tot were obtained. The concentration dependency of N I tot and r I tot leads to the conclusion, that the Bi-In melts belong to the compound forming melts.

Open Access June 2, 2014

Ultraschall-Geschwindigkeit und-Absorption in Bi-In-Schmelzen /Ultrasonic Velocity and Absorption in Bi-In-melts

R. Bek, S. Steeb

Page range: 154-164

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Abstract

Using the pulse-echo method the ultrasonic velocity and absorption was measured with Bi-In-melts in the temperature range from liquidus up to more than 600 °C. The frequencies used reached from 10 MHz up to 130 MHz. Within the experimental accuracy no frequency dependence of the absorption coefficient α/f 2 could be detected. An excess absorption can be observed, which for the molten elements can be explained by fluctuations of the packing density. For the molten alloys additionally concentration fluctuations play an important role. Thus an understanding of the temperature dependency of the ultrasonic velocity and absorption can be achieved.

Open Access June 2, 2014

X-Ray and Neutron Diffraction Studies on Amorphous Transitionmetal—Boron Alloys (Fe-B,Co-B,Ni-B)

P. Lamparter, E. Nold, G. Rainer-Harbach, E. Grallath, S. Steeb

Page range: 165-172

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Abstract

The atomic-scale structure of the amorphous metallic alloys Fe 80 B 20 , Co 81·5 B 18·5 , and Ni 81·5 B 18·5 was investigated by X-ray- and neutron-diffraction covering a wide range of the ratio (f metal /f boron ) of the scattering factors of both components. The structure factors S (q) show a pronounced dependence on the ratio f metal /f boron . In the cases of a small ratio an additional peak near q = 21.5 nm -1 appears in the structure factors from which a definite distance between B-B atoms, which are separated by metal atoms, is deduced. The corresponding structure factors show only weak oscillations in the range of the second and third maxima, which are followed by increased amplitudes at larger q's. By Fourier-transformation radial distribution curves were evaluated, from which the distances between the metal-metal-, the metal-boron-, and the boron-boron-atoms and the coordination numbers are extracted. From the splitted first maximum of the radial distribution function in the cases of small ratio f metal /f boron also partial coordination numbers could be obtained. The results suggest some kind of short range order between the metal and the boron atoms.

Open Access June 2, 2014

Some Investigations of the Chemiluminescence Spectra from the Reactions of Ca and Sr with SF₆

W. Berneike, H. J. Löffler, H. Neuert

Page range: 173-176

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Abstract

The appearance of the chemiluminescence spectra from the reactions of the alkaline earth metals M = Ca and Sr with SF 6 is only understood by the participation of excited metal atoms in the reactions. This has been ascertained by measuring the dependence of the intensities of the metastable Ca-line 657.3 nm and of a representative CaF band on the SF 6 gas pressure in the reaction chamber. By a detailed analysis of the well resolved A -X-and B - X-systems of both of the reactions some earlier values of Do(F-SF 5 ) given in the literature can be excluded, while the recently found value (Kiang et al.) of 3.9 ±0.14 eV is well confirmed.

Open Access June 2, 2014

Optical Measurements of Tropospheric Hydroxyl with Lasers

G. Ortgies, K.-H. Gericke, F. J. Comes

Page range: 177-183

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Abstract

The application of laser induced fluorescence (LIF) in the uv to monitor tropospheric OH concentrations is limited for several reasons. In general the sensitivity of this method increases with the laser intensity. But at the low OH concentrations present in the atmosphere the beginning nonlinearity of the absorption (saturation effect) severely restricts the use of higher laser intensities. The high sensitivity of the LIF technique can be further compromised by the presence of an OH interference signal. This signal is generated by the monitoring laser light itself from laser photolysis of ambient ozone and the succeeding reaction of the photolysis product O ( 1 D) with water to produce hydroxyl radicals. The results of the calculations are presented in a diagram from which the range of laser parameters can be deduced, which can be applied with confidence to monitor OH by the LIF method. The maximum number of signal counts for these working conditions is in the range of 10 -3 per laser pulse.

Open Access June 2, 2014

Lattice Vibration Spectra XXIV*. Far-Infrared Reflection Spectra, Optical and Dielectric Constants, and Effective Charges of the Pyrite Type Compounds FeS₂, MnS₂, MnSe₂, and MnTe₂

H. D. Lutz, G. Kliche, H. Haeuseler

Page range: 184-190

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Abstract

From the far-infrared reflection spectra of the pyrite type compounds FeS 2 , MnS 2 , MnSe 2 , and MnTe 2 we determined the TO and LO phonon frequencies at wave vector | q | ≈ 0 by both Kramers-Kronig analysis and classical oscillator fit method. In the case of MnSe 2 and MnTe 2 we found for the first time all five group-theoretically allowed reststrahlen bands. The phonon frequencies obtained from both single crystal and pressed pellet reflection measurements do not show any significant differences. The calculated optical and dielectric constants however are strongly affected by the surface quality of the sample. Effective ionic charges (Born effective charge, Szigeti charge) were calculated from the experimentally determined TO/LO splittings. They demonstrate an increasing ionicity in the order FeS 2 <MnTe 2 <MnSe 2 <MnS 2 .

Open Access June 2, 2014

Fluorescence and Absorption Spectra of Phenylazopyrazolone Dyes

Peter Nikolov, Filip Fratev, Stefan Stoyanov, Oskar E. Polansky

Page range: 191-196

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Abstract

The absorption and fluorescence spectra of some arylazopyrazolone dyes have been investigated. The emission is assigned to their hydrazone form. A very good linear correlation is obtained between the σ Hammett constants and the differences of the absorption maxima of the hydrazone form and the anion. Quantum chemical calculations indicate to a charge migration upon excitation. The electron donor substituents cause bathochromic and hypsochromic shifts in the absorption and in the fluorescence maxima resp., while the acceptor substituents shift bathochromically both maxima. All compounds studied except the p-N(CH 3 ) 2 derivative show an anomalously large Stokes shift in nonpolar solvents.

Open Access June 2, 2014

Zur Korrelation von 0-0-Übergängen, Absorptions- und Fluoreszenzmaxima mit σ-Hammett-Konstanten / The correlation of the 0-0-transitions and the maxima of absorption and fluorescence with theσ-Hammett constants.

O. E. Polansky, F. Fratev, P. Nikolov

Page range: 197-202

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Abstract

The correlation of the 0-0-transitions and the maxima of absorption and fluorescence with the σ-Hammett constants. The correlation of the 0-0-transitions and the maxima of absorption and fluorescence with the ff-Hammett constants lead to conclusions concerning the changes in the gap of the state involved and their curvatures due to substitution. The formalism can be applied also using other LFER parameters than σ-Hammett constants.

Open Access June 2, 2014

EPR Study of Hydration of Portland Cement

D. D. Lasič, G. Lahajnar, R. Blinc, I. Kocuvan

Page range: 203-204

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Abstract

The microscopic nature of the solidification of cement was studied via a measurement of the time dependence of the fraction of freely rotating spin probes by electron paramagnetic resonance with and without added retardants. The results seem to support the osmotic theory of cement hydration.

About this journal

Objective
A Journal of Physical Sciences: Zeitschrift für Naturforschung A (ZNA) is an international scientific journal which publishes original research papers from all areas of experimental and theoretical physics. Authors are encouraged to pay particular attention to a clear exposition of their respective subject, addressing a wide readership. In accordance with the name of our journal, which means “Journal for Natural Sciences”, manuscripts submitted to ZNA should have a tangible connection to actual physical phenomena. In particular, we welcome experiment-oriented contributions.

Manuscripts considered for publication in A Journal of Physical Sciences: Zeitschrift für Naturforschung A undergo high-level refereeing. Mere formal correctness of a paper is not sufficient for its acceptance. Moreover, articles reporting a merely marginal extension of already existing knowledge are considered unsatisfactory. Instead, the key quality a publication in A Journal of Physical Sciences: Zeitschrift für Naturforschung A should possess is that it makes a genuine contribution to the advancement of its topic.

Topics

Atomic, Molecular & Optical Physics
Chemical Physics
Dynamical Systems & Nonlinear Phenomena
Fundamental Concepts of Physical Sciences
Gravitation & Cosmology
Hydrodynamics & Plasma Physics
Nuclear Physics & Particle Physics
Quantum Field Theory
Solid State Physics & Materials Science
Thermodynamics & Statistical Physics
Article formats
Original research articles, research notes, letters and review articles from all areas of theoretical and experimental physics

Information on submission process

Volume 36 Issue 2

Issue of Zeitschrift für Naturforschung A

On the Inversion of the Linearized Collision Operator

Abstract

Strong Collision Induced Spin-Lattice Relaxation for Tunneling NH4-ion Systems in the Rotating Frame

Abstract

Topological Resonance Energy of Very Large Benzenoid Hydrocarbons

Abstract

Low-Energy e-He(21L) Scattering Calculations

Abstract

Carbon Contaminant Buildup and Sputtering Behaviour on Zinc Oxide During XPS Examination

Abstract

Three-dimensional Analytical Force-free MHD Equilibria

Abstract

Röntgen-Beugungsuntersuchungen an Bi-In-Schmelzen / X-Ray Diffraction Experiments with Bi-In-melts

Abstract

Ultraschall-Geschwindigkeit und-Absorption in Bi-In-Schmelzen /Ultrasonic Velocity and Absorption in Bi-In-melts

Abstract

X-Ray and Neutron Diffraction Studies on Amorphous Transitionmetal—Boron Alloys (Fe-B,Co-B,Ni-B)

Abstract

Some Investigations of the Chemiluminescence Spectra from the Reactions of Ca and Sr with SF6

Abstract

Optical Measurements of Tropospheric Hydroxyl with Lasers

Abstract

Lattice Vibration Spectra XXIV*. Far-Infrared Reflection Spectra, Optical and Dielectric Constants, and Effective Charges of the Pyrite Type Compounds FeS2, MnS2, MnSe2, and MnTe2

Abstract

Fluorescence and Absorption Spectra of Phenylazopyrazolone Dyes

Abstract

Zur Korrelation von 0-0-Übergängen, Absorptions- und Fluoreszenzmaxima mit σ-Hammett-Konstanten / The correlation of the 0-0-transitions and the maxima of absorption and fluorescence with theσ-Hammett constants.

Abstract

EPR Study of Hydration of Portland Cement

Abstract

Strong Collision Induced Spin-Lattice Relaxation for Tunneling NH₄-ion Systems in the Rotating Frame

Low-Energy e-He(2¹L) Scattering Calculations

Some Investigations of the Chemiluminescence Spectra from the Reactions of Ca and Sr with SF₆

Lattice Vibration Spectra XXIV*. Far-Infrared Reflection Spectra, Optical and Dielectric Constants, and Effective Charges of the Pyrite Type Compounds FeS₂, MnS₂, MnSe₂, and MnTe₂