The influence of homeotropic boundary conditions on the cholesteric-nematic transition is discussed, starting from the assumption that the director field consists of only components perpendicular to the helix axis, which is directed parallel to the boundary planes. Attention is paid to the solution of Cladis and Kléman for the simpler case without magnetic field. Their solution, consisting of regularly spaced line signularities, is derived in another more transparent way. Besides it is shown that even director fields without singularities are possible. The presence of a magnetic field complicates the solution considerably. Now the relevant Euler-Lagrange equation is solved in an approximate way by partly resorting to the difference method. The usefulness of the method is demonstrated by applying this technique to the nematic-cholesteric transition and the Fréedericksz transition in nematics.

Open Access June 2, 2014

Surface Polariton Mode Densities

W. Eckhardt

Page range: 10-15

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Abstract

Starting from the Green functions of the electromagnetic (EM) field in two adjacent dielectric half-spaces, the surface and bulk contributions to the EM-density of states are discussed. The mode densities determine the thermodynamic properties of the radiation field.

Open Access June 2, 2014

Dipole Moment Functions of HF and HI Molecules Using an Anharmonic Potential

Manfred H. Kluckner, B. Sesh Rao

Page range: 16-19

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Abstract

Vibration-rotation wave functions for HF and HI are computed by solving the radial Schroedinger wave equation numerically using an anharmonic potential function with seven adjustable parameters. With these wave functions the matrix elements of [(r - r e )/r e ] n are computed. These are then applied in a least squares fit to experimentally measured values of the electric dipole matrix elements to yield the dipole moment coefficients M 0 , M 1 ,..., M 5 .

Open Access June 2, 2014

Evidence for Different Ferromagnetic Phases in Amorphous Fe₄₀Ni₄₀B₂₀ Detected by EPR

R. Gerling

Page range: 20-26

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Abstract

Amorphous ferromagnetic Fe 40 Ni 40 B 20 (T c = 662 K) has been investigated by EPR in the temperature range from 110 to 510 K. From the temperature dependence of the magnetic field at resonance, the saturation magnetization could be evaluated. Around 470 K the line width of the resonance signal exhibits a pronounced minimum, and the EPR-intensity deviates at this temperature from pure ferromagnetic behaviour. Both effects can be explained by assuming the presence of a second ferromagnetic phase with a Curie temperature of T c ′=470 K. Upon annealing of Fe 40 Ni 40 B 20 at temperatures slightly higher than T c ′ changes in physical properties, such as Curie temperature, density and relative strain at fracture are observable. It is proposed that the onset of the low temperature relaxation which is responsible for these changes in physical properties is related to the transition of the second ferromagnetic phase to the paramagnetic state.

Open Access June 2, 2014

Schwingungsspektren von Ag₃PS₄ und Cu₃PS₄ / Vibrational Spectra of Ag₃PS₄ and Cu₃PS₄

Page range: 27-30

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Abstract

The infrared and Raman spectra of silver thiophosphate Ag 3 PS 4 have been recorded. The observed frequencies are assigned on the basis of tetrahedral units by considering a splitting of the F 2 modes by the crystal field. The vibrational frequencies of copper thiophosphate Cu 3 PS 4 are completed for the far infrared region. For both title compounds DTA-data have been determined and interpreted.

Open Access June 2, 2014

IR Studies of Crystalline Methanol Films with Textures

F. Fischer, R. Fuhrich

Page range: 31-36

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Abstract

When amorphous methanol films, deposited at 78 K on a substrate already covered by a thin crystalline methanol layer, are crystallized above 104 K they obtain a growth texture. This can be seen from relative intensity alterations of IR bands related to the hydrogen bondings. Another growth texture is obtained by depositing the film at 145 K. Large spherulites are seen between crossed polarizers. Other alterations of IR bands are observed. From the interpretation of this dichroism we learn about the growth mechanism. The relations of polymer chains with hydrogen bonds to those with covalent bonds are discussed. Isothermal sublimation can be studied from the linear decrease of a single IR band. This allows to determine the heat of sublimation.

Open Access June 2, 2014

Experimental Study of Ion Dynamic Effects in Overlapping Helium Lines at Low Densities

A. Piel, H. Richter

Page range: 37-46

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Abstract

The line profiles of the overlapping helium lines 447.1 nm and 492.2 nm have been investigated in an improved plasma source of high purity at electron densities of 1 × 10 21 m −3 and 3 × 10 21 m −3 . The plasma parameters N e , T e and T 0 were determined carefully by independent diagnostics, which enables a critical comparison with existing theories (BCS II and MMM). We observed ion dynamic effects which considerably modify the line shape of the forbidden components. Our experiments extend the existing observations towards higher ion temperatures. Systematic trends observed earlier are critically discussed.

Open Access June 2, 2014

Intensity Analysis and Luminescence Spectra of Non-Aqueous Solutions of Europium Compounds

Janina Legendziewicz, Grażyna Oczko, Wiesław Stręk

Page range: 47-55

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Abstract

The oscillator strengths of the f-f transitions as well the fluorescence spectra for europium Perchlorate, chloride and nitrate in mono- and disubstituted amides have been measured. The Judd-Ofelt parameters are calculated. The formation of inner-sphere europium complexes is discussed on the basis of intensity analysis of the absorption and luminescence spectra. In mono- and disubstituted amides solutions the f-f transitions of Eu +3 have been analysed and the three parameters fitted with satisfactory accuracy. Among all f-f transitions the hypersensitive ones in absorption 7 F 0 → 5 D 0 and fluorescence 5 D 0 → 7 F 2 varied most markedly. From an analysis of the data it was concluded that only Eu(NO 3 ) 3 and EUCl 3 in DMF form inner-sphere complexes. At low concentration of EUCl 3 in DMF the predominant form is [EuCl(DMF) y−1 ] +2 , whereas at high concentration the predominant form is [EUCl 2 (DMF) y−2 ] +1 . The intensity of the hypersensitive bands decreases with increasing EUC1 3 concentration, contrary to the common opinion that complexation increases the intensity of hypersensitive bands.

Open Access June 2, 2014

Photophysical Study of a Series of Cyanines Part III. The direct photooxidation reaction

Shukri Lepaja, Henry Strub, Daniel-Joseph Lougnot

Page range: 56-60

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Abstract

The main degradative pathway of tricarbocyanine dyes in aerated solutions is demonstrated to be a photooxidation; using sensitization techniques and specific quenchers, this reaction is established to proceed via singlet oxygen for a part, and the site at which this species attacks the polymethinic skeleton is unambiguously determined. The major photoproduct is identified as being 1,3,3-trimethyl-2-indolinone.

Open Access June 2, 2014

Semiempirical Calculation of the Rotational Barrier and Valence Force Constants in Fluorocarbonylsulfenyl Chloride

A. H. Jubert, C. O. Della Védova, E. L. Varetti, O. E. Piro, P. J. Aymonino

Page range: 61-63

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Abstract

The rotational barrier about the C-S bond in fluorocarbonylsulfenyl chloride [FC(O)SCl] is investigated using the CNDO method. The results confirm the existence of planar eis and trans conformers and the higher stability of the latter, as suggested by previous vibrational results. The valence force constants in FC(O)SCl were also calculated and the values obtained compare favourably with results from a previous normal coordinate calculation and with those of related compounds.

Open Access June 2, 2014

Rotational Spectrum of Methylcyanoacetylene A New Millimeter Wave Spectrometer

M. Bester, M. Tanimoto, B. Vowinkel, G. Winnewisser, Koichi Yamada

Page range: 64-67

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Abstract

The ground state rotational spectrum of methylcyanoacetylene, CH 3 CCCN, has been observed between 8 and 90 GHz, yielding precise rotational constants and a determination of the nuclear hyperfine costant eqQ = -4.0 ± 0.2 MHz. The millimeter wave spectra (70 - 90 GHz) were obtained with a newly constructed spectrometer, employing a synthesizer - controlled reflex klystron as source.

Open Access June 2, 2014

Bestimmung der Aktivierungsparameter für die N-Inversion im 4-[(2,2-Dimethyl-aziridino-(1))-methyl]-2,6-di-tert.butyl-phenol durch ¹H-DNMR / Evaluation of Activation Parameters for the N-Inversion of 4-[(2,2-Dimethyl-aziridino-(1))-methyl]- 2,6-di-tert.butyl-phenol by ¹H-DNMR

Page range: 68-73

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Abstract

Parts of the 1 H-NMR spectra of the title substance show typical coalescence behaviour, which is analysed by line shape simulation. N-inversion is accounted for the dynamic process and rate constants and activation energies are given.

Open Access June 2, 2014

The Electronic Spectrum and Structure of Tetrasulfur Dinitride

Michael H. Palmer

Page range: 74-77

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Abstract

Ab initio configuration interaction calculations of the ground and singlet A′ and A″ excited states have been performed, with all possible single and double excitations from the 10 highest occupied orbitals to the lowest 17 virtual orbitals being included, the previous C s symmetry molecular structure being used. Some of the states can be identified with excitation from individual occupied (SCF) orbitals to members of the virtual set, but some are not well represented by single configuration concepts. The results suggest that the three broad UV-spectral maxima observed in solution are not single excitations, but groups of excited states, with a total of 8 states. The closeness of some of these states makes positive assignment difficult. The most probable assignment is 455 nm (1 A″), 377 nm (2A″ + 1A′+ 2A′), ~ 277 nm (3A″ + 3A′), 232 nm (4A′ + 4A″).

Open Access June 2, 2014

The Electronic Structure of Tetraphosphorus-and Tetraarsenic- Trisulphides; Interpretation of their Photoelectron Spectra

Michael H. Palmer, Robert H. Findlay

Page range: 78-85

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Abstract

Ab initio SCF calculations of the X 1 A 1 ground states of P 4 S 3 and As 4 S 3 are reported, together with configuration interaction studies of the 2 A 1 , 2 A 1 , 2 A 2 and 2 E states of P 4 S 3 . A re-interpretation of the UV-photoelectron spectrum of the P 4 S 3 molecule, and As 4 S 3 by analogy, is presented and it is noted that Koopmans′ theorem yields a very similar order and spacing between groups to the doublet states computed by configuration interaction.

Open Access June 2, 2014

Notizen: Bäcklund Transformation Groups of Non-Linear Evolution Equations and the Painlevé Property

W.-H. Steeb, W. Oevel

Page range: 86-87

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Abstract

We show that the group theoretical reduction of evolution equations which admit Lie-Bäcklund transformation groups does not lead in general to ordinary differential equations with the Painlevé property.

Open Access June 2, 2014

Notizen: Excess Free Energies in Molten CuCl-KCl-LiCl by EMF Measurements

Z. Giazitzoglou, H. Engels, U. Schiller

Page range: 88-89

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Abstract

The ternary liquid system CuCl-KCl-LiCl has been investigated by means of emf measurements at about 450 up to 700 °C. Excess free energies and activity coefficients for molten CuCl in the KCl-LiCl eutectic are calculated by a best fit to the obtained data and from literature data for the corresponding binary systems employing the Redlich-Kister equation.

Open Access June 2, 2014

Dipole Moments and Configurations of Triaryl Acrilonitriles

D. Carbone, A. Chisari, E. Montoneri, G. C. Pappalardo, G. Scarlata

Page range: 90-94

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Abstract

The electric dipole moments of trans-1,2 diaryl acrilonitrile 1 and of a series of triaryl acrilonitriles 2-14 were measured in benzene solution at 25 °C. A mesomeric moment of 0.4 D was found to act between the phenyl-and the nitrile groups through the vinylic bond in triaryl acrilonitrile 2. For this molecule the direction of action of the total molecular moment was calculated and used to evaluate theoretical moments for the possible E and Z configurations of some unsymmetrical derivative compounds of the series. The configuration was settled for each com-pound on the basis of comparison between experimental and calculated dipole moment values.

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 38 Issue 1

Issue of Zeitschrift für Naturforschung A

Titelei

Inhaltsverzeichnis

On the Field-Induced Cholesteric-Nematic Transition in Cholesteric Liquid Crystals with Homeotropic Boundary Conditions

Abstract

Surface Polariton Mode Densities

Abstract

Dipole Moment Functions of HF and HI Molecules Using an Anharmonic Potential

Abstract

Evidence for Different Ferromagnetic Phases in Amorphous Fe40Ni40B20 Detected by EPR

Abstract

Schwingungsspektren von Ag3PS4 und Cu3PS4 / Vibrational Spectra of Ag3PS4 and Cu3PS4

Abstract

IR Studies of Crystalline Methanol Films with Textures

Abstract

Experimental Study of Ion Dynamic Effects in Overlapping Helium Lines at Low Densities

Abstract

Intensity Analysis and Luminescence Spectra of Non-Aqueous Solutions of Europium Compounds

Abstract

Photophysical Study of a Series of Cyanines Part III. The direct photooxidation reaction

Abstract

Semiempirical Calculation of the Rotational Barrier and Valence Force Constants in Fluorocarbonylsulfenyl Chloride

Abstract

Rotational Spectrum of Methylcyanoacetylene A New Millimeter Wave Spectrometer

Abstract

Bestimmung der Aktivierungsparameter für die N-Inversion im 4-[(2,2-Dimethyl-aziridino-(1))-methyl]-2,6-di-tert.butyl-phenol durch 1H-DNMR / Evaluation of Activation Parameters for the N-Inversion of 4-[(2,2-Dimethyl-aziridino-(1))-methyl]- 2,6-di-tert.butyl-phenol by 1H-DNMR

Abstract

The Electronic Spectrum and Structure of Tetrasulfur Dinitride

Abstract

The Electronic Structure of Tetraphosphorus-and Tetraarsenic- Trisulphides; Interpretation of their Photoelectron Spectra

Abstract

Notizen: Bäcklund Transformation Groups of Non-Linear Evolution Equations and the Painlevé Property

Abstract

Notizen: Excess Free Energies in Molten CuCl-KCl-LiCl by EMF Measurements

Abstract

Dipole Moments and Configurations of Triaryl Acrilonitriles

Abstract

Evidence for Different Ferromagnetic Phases in Amorphous Fe₄₀Ni₄₀B₂₀ Detected by EPR

Schwingungsspektren von Ag₃PS₄ und Cu₃PS₄ / Vibrational Spectra of Ag₃PS₄ and Cu₃PS₄

Bestimmung der Aktivierungsparameter für die N-Inversion im 4-[(2,2-Dimethyl-aziridino-(1))-methyl]-2,6-di-tert.butyl-phenol durch ¹H-DNMR / Evaluation of Activation Parameters for the N-Inversion of 4-[(2,2-Dimethyl-aziridino-(1))-methyl]- 2,6-di-tert.butyl-phenol by ¹H-DNMR