Published by De Gruyter

Volume 52 Issue 11

Issue of Zeitschrift für Naturforschung A

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Open Access June 2, 2014

Proton Spin-lattice Relaxation in Amorphous States of Organic Molecular Solids

M. T. Myaing, L. Šekarić, P. A. Beckmann

Page range: 757-764

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Abstract

We have measured the temperature dependence of the proton spin-lattice relaxation rate R at 8.50 and 22.5 MHz in solid 1,3,5-tri-ethyl-benzene and solid 1,2,4-tri-ethyl-benzene. Analysis of the data strongly suggests that we are studying amorphous states in these slowly solidified organic solids (that are liquids at room temperature). The ethyl groups are static on the Larmor frequency time-scale. There are no simple-model interpretations of the data, but a reasonable model for the dominantly-occurring amorphous state data observed with 1,3,5-tri-ethyl-benzene suggests that two of the three methyl groups are reorienting and the third is static on the proton Larmor frequency time scale. The same approach for the two amorphous states observed in 1,2,4-tri-ethyl-benzene suggests that all three methyl groups are reorienting in one state and that three of the six methyl groups in each pair of molecules are turned off in a second state. We discuss that, whereas specific dynamical statements are model dependent, the proton spin relaxation technique does make some general qualitative statements about the mesostructure of the solid.

Open Access June 2, 2014

EPR Study of VO²⁺ and Cr³⁺ in Li₂SO₄ · H₂O Single Crystal

F. Çelik, F. Köksal, İ. Kartal, H. Gümüş

Page range: 765-770

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Abstract

A single crystal X-band EPR study of VO 2+ and Cr 3+ in Li 2 SO 4 • H 2 O was carried out at room temperature. Analysis of the spectra indicates that VO 2+ substitutes for Li + and that there are two magnetically inequivalent Li + sites. The charge compensation occurs by removal of a neighboring Li + . The principal values of the g and A tensors of the spin Hamiltonian for the two sites were determined. Superhyperfine interaction of the 3d 1 electron of VO 2+ with the neighboring water protons in the unit cell was observed and found to be between 0 and 0.5 mT, depending on the orientation of the magnetic field. Two magnetically different sites were also observed for Cr 3+ , and the results were explained by a rhombic spin Hamiltonian. The Hamiltonian parameters g, D, and E were determined. It is concluded that VO 2+ and Cr 3+ enter into the Li + places and the charge is compensated by a Li + vacancy in the VO 2+ case and proton vacancies in the Cr 3+ case.

Open Access June 2, 2014

Spectral-Interferometry Measurements of Copper Atom Concentration in a Segmented Hollow Cathode Discharge

L. Szalai, M. Ulbel, T. Neger, G. Pretzler, Z. Donkó, K. Rózsa, R. C. Tobin

Page range: 771-777

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Abstract

We report spectral-interferometry measurements of the concentration and the spatial distribution of copper vapor in a high voltage, segmented hollow cathode discharge, which is an efficient source for laser light generation. The concentration of sputtered copper atoms was found to be in the order of 10 14 cm -3 at currents of 0.6-1.0 A in a 5 cm long, 4 mm bore diameter discharge tube, operating in argon buffer gas. At high pressures and relatively low current densities the sputtered metal concentration forms two maxima near the cathode surface. With increasing current and decreasing pressure these two maxima move towards the center of the discharge. This result may account for the fact that at certain discharge parameters the segmented hollow cathode lasers operate in higher order transverse modes near the threshold. The measurements of copper vapor concentration show increased sputtering compared to conventional hollow cathodes, which is considered to be one of the reasons for segmented hollow cathode metal ion lasers being more efficient.

Open Access June 2, 2014

Ultrasonic Studies of Ferroelectric Phase Transition in Gly-H₃PO₃ Crystals

J. Furtak, Z. Czapla, A.V. Kityk

Page range: 778-782

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Abstract

The temperature behaviour of the longitudinal and transverse ultrasound wave velocities and attenuation in the region of the ferroelectric phase transition (T c = 225 K) of the glycine phosphite (Gly-H 3 PO 3 ) crystals is studied. The obtained results are considered within the framework of phenomenological theory.

Open Access June 2, 2014

NMR Study of Cation Motion in Guanidinium Iodoplumbates

M. Grottel, M. Szafrański, Z. Pająk

Page range: 783-788

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Abstract

Proton NMR second moments and spin-lattice relaxation times of polycrystalline C(NH 2 ) 3 PbI 3 and [C(NH 2 ) 3 ] 2 PbI 4 were studied in a wide temperature range. The order-disorder character of the existing solid-solid phase transitions was confirmed and for tetraiodoplumbate a new phase transition at 170 K was discovered. For both compounds a dynamical inequivalence and unusual high mobility of the guanidinium cations were revealed. For the reorientations discovered (NH 2 group flipping, C 3 in-plane reorientation and a tumbling) the activation parameters were determined.

Open Access June 2, 2014

Zonar Distribution of ¹⁸O in Synthetic Quartz Crystals

A. Klemm, K. Röller, S. Hoernes

Page range: 789-792

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Abstract

The 18 O-content in the mantle-zones of a commercial synthetic quartz was found to increase from the seed towards the surface by 7 ‰. Since the growth took place in a closed container, calculations for the evolution towards the steady state of the 18 O-transport could be performed. In the steady state the concentrations of 18 O and impurities in the growing quartz are uniform.

Open Access June 2, 2014

The Use of Parameter-Free Correlation Functions in Green's Function Monte Carlo Simulations of Small Electronic Systems

C. Mecke, F. F. Seelig

Page range: 793-802

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Abstract

Using an old formulation for correlation functions with correct cusp-behaviour, the Schrödinger equation transforms to a new differential equation which provides a very simple expression for the local electronic energy with limited range. This, together with the simplicity of the formulation promises a high performance in Green's function Monte Carlo (GFMC) simulations of small electronic systems. The behaviour of the local energy is studied on a few simple examples because the variance of this function determines the quality of the results in the GFMC methods. Calculations for one-and two-electron systems are presented and compared with results from well-known functions. The form of the function is then extended to systems with more than two electrons. Results for the Be atom are given and the extension to larger electronic systems is discussed.

Open Access June 2, 2014

The Microwave Spectrum of the Bimolecule Trifluoroacetic Acid · · · Cyclopropanecarboxylic Acid

Sonja Antolínez, Helmut Dreizler, Volker Storm, Dieter H. Sutter, José L. Alonso

Page range: 803-810

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Abstract

We have investigated the microwave spectrum of the bimolecule trifluoroacetic acid • • • cyclo-propanecarboxylic acid in the region 1 to 4 GHz, where the low J transitions of this heavy complex appear. The measured μ a -R branch transition frequencies were fitted to determine the rotational constants and three centrifugal distortion constants. With the assumption that the structures of the subunits remain unchanged upon complexation, the O • • • O distances of the hydrogen bridge bonds are determined as 2.62 A.

Open Access June 2, 2014

Hydrogen Isotope Fractionation in Aqueous Alkali Halide Solutions

Masahisa Kakiuchi

Page range: 811-820

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Abstract

The D/H ratios of hydrogen gas in equilibrium with aqueous alkali halide solutions were deter-mined at 25 °C, using a hydrophobic platinum catalyst. The hydrogen isotope effect between the solution and pure water changes linearly with the molality of the solution at low concentrations, but deviates from this linearity at higher concentration for all alkali halide solutions. The magnitude of the hydrogen isotope effect is in the order; Kl > Nal > KBr > CsCl ≧ NaBr > KCl > NaCl > LiCl, at concentrations up to a molality of 4 m. The sign and trend of the hydrogen isotope effect is different from that of oxygen. In aqueous alkali halide solutions, the hydrogen isotope effect is influenced by both the cation and the anion species, while the oxygen isotope effect is mainly caused by the cation species. This suggests that the mechanism of hydrogen isotope fractionation between the water molecules in the hydration spheres and the free water molecules differs from the mechanism of the oxygen isotope fractionation. The hydrogen and oxygen isotope effects for alkali halides, except LiCl and NaCl, may be influenced by changes in energy of the hydrogen bonding in free water molecules.

Open Access June 2, 2014

Boron Isotope Effect in Liquid Chromatography with Boron-specific Resins as Packing Material

Takao Oi, Hirotsugu Takeuchi, Akiko Sakurai, Yoshifumi Taguchi, Morikazu Hosoe

Page range: 821-827

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Abstract

Boron isotope separation by liquid chromatography using boron specific resins with N-methyl glucamine as the functional group was performed. The single-stage separation factor, S, is generally dependent on the resin in the sequence S (free base form resin) > S (F - form resin) >S (Cl - form resin) ≧S (Br - form resin) for given experimental conditions. This sequence is the same as that of the pH value expected in the resin phase and reasonably understandable by assuming in addition to the predominant four-coordinate species a three-coordinate boron species in the resin phase whose relative abundance increases with decreasing pH. Supporting evidence for three-coordinate species was obtained by 1: B NMR measurements of boric acid-glycerol and boric acid-1,3-propane-diol solutions.

Open Access June 2, 2014

Cluster Formation in a Concentrated Lithium-Liquid Ammonia Solution. A Monte Carlo Study

S. Hannongbua, S. Kokpol, Z. Gurskii, K. Heinzinger

Page range: 828-834

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Abstract

Results of a Monte Carlo study of a lithium-liquid ammonia solution at 240 K are reported. The basic cube contained 135 Li + and 1025 NH 3 . With an experimental density of 0.554 g/cm 3 a side-length of 37.89 Å resulted. The pseudopotential theory is employed, which permits the exclusion of the electrons from an explicit consideration. The structure of the solution is described by various site-site radial distribution functions. The six ammonia molecules in the first solvation shell of the lithium ion are arranged octahedrally. Clusters are formed which consist almost exclusively of two solvated Li + which have simultaneously either one ammonia molecule or an octahedral edge or an octahedral plane in common. About one third of the ammonia molecules belong to the bulk phase.

Open Access June 2, 2014

Notiz: An Explanation of the Paradox Underlying the Trouton-Hildebrand-Everett Rule

J. J. Rooney

Page range: 835-835

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Abstract

The Trouton-Hildebrand-Everett rule, which is a refinement of Trouton's rule, requires that the so-called molar liquid free volume, V 1 0 in the expression ΔS b 0 = Rln(V g 0 / V 1 0 ) for the entropy of vapourization of molecular liquids is a constant with a volume of 1.5 cm, whereas V g 0 , the corresponding vapour free volume, is directly dependent on the value of the boiling point, T b . This paradox is resolved using a statistical mechanical rationale for ideal systems which shows that V 1 0 is in reality N times a molecular volume derived from a characteristic distance in the liquid-vapour transition state. This distance is the same for all ideal molecular liquids.

Open Access June 2, 2014

Erratum

Page range: 836-836

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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 & Chemical Physics
Dynamical Systems & Nonlinear Phenomena
Gravitation & Cosmology
Hydrodynamics
Quantum 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 52 Issue 11

Issue of Zeitschrift für Naturforschung A

Proton Spin-lattice Relaxation in Amorphous States of Organic Molecular Solids

Abstract

EPR Study of VO2+ and Cr3+ in Li2SO4 · H2O Single Crystal

Abstract

Spectral-Interferometry Measurements of Copper Atom Concentration in a Segmented Hollow Cathode Discharge

Abstract

Ultrasonic Studies of Ferroelectric Phase Transition in Gly-H3PO3 Crystals

Abstract

NMR Study of Cation Motion in Guanidinium Iodoplumbates

Abstract

Zonar Distribution of 18O in Synthetic Quartz Crystals

Abstract

The Use of Parameter-Free Correlation Functions in Green's Function Monte Carlo Simulations of Small Electronic Systems

Abstract

The Microwave Spectrum of the Bimolecule Trifluoroacetic Acid · · · Cyclopropanecarboxylic Acid

Abstract

Hydrogen Isotope Fractionation in Aqueous Alkali Halide Solutions

Abstract

Boron Isotope Effect in Liquid Chromatography with Boron-specific Resins as Packing Material

Abstract

Cluster Formation in a Concentrated Lithium-Liquid Ammonia Solution. A Monte Carlo Study

Abstract

Notiz: An Explanation of the Paradox Underlying the Trouton-Hildebrand-Everett Rule

Abstract

Erratum

EPR Study of VO²⁺ and Cr³⁺ in Li₂SO₄ · H₂O Single Crystal

Ultrasonic Studies of Ferroelectric Phase Transition in Gly-H₃PO₃ Crystals

Zonar Distribution of ¹⁸O in Synthetic Quartz Crystals