bluuebunny/crossref_metadata_2025 huggingface dataset:
Dispersion der gekoppelten Wellen beim stimulierten Raman-Effekt unter Berücksichtigung der dielektrischen Dispersion / Dispersion of Coupled Waves of Stimulated Raman-Effect with Regard to Dielectric Dispersion
Authors: Merten L. , Wenk J.
Published: February 2015

It is shown that the dispersion functions of coupled waves depend very sensitively on the dielectric dispersion in the visible frequency region. The dispersion functions of all six coupled waves can be described by explicit formulae in very good approximation.
Experimental Profiles of the Balmer Line Hβ Emitted from an Afterglow Plasma Without and With a Superposed Magnetic Field up to 10 Tesla
Authors: Drawin H. W. , Ramette J.
Published: February 2015

The profile of the Hβ line emitted from an afterglow plasma in pure hydrogen gas and a mixture of hydrogen and helium has been measured in axial direction using a multichannel spectrum analyzer with additional temporal resolution. Measurements were performed without and with a superposed magnetic field (B ≦ 10.8 Tesla) in axial direction. With magnetic field we observed a rather strong dependence of the wavelength positions of the two lateral "Zeeman components" (intensity maximum due to combined Stark-Zeeman effects). This feature is important in radiative transfer calculations and for the spectroscopic determination of magnetic fields in plasmas. - Both with and without magnetic field we always observed a line structure superposed on the Hβ profile. The structure disappeared in an active electrical discharge and changed with gas composition. The line structure is interpreted as being due to electronic transitions of molecular hydrogen. It is very probable that the "satellite structures" of Balmer lines observed by other authors under quite different experimental conditions and interpreted as dynamical Stark effect splitting due to fluctuating electric fields have in most cases the same molecular origin. Our earlier published line profiles of Hβ for B = 0 [J. Ramette and H. W. Drawin, Z. Naturforsch. 31 a, 401 (1976) ] are revised in the present paper.
Radiation Pressure Dominated Plasma Flow
Authors: Mulser P. , Spindler G.
Published: February 2015

The influence of light pressure on plane and spherical plasma flows is treated. Numerical calculations show that smooth laser pulses lead to formation of an overdense plateau if thermal transport is non-negligible there, and that an originally supersonic flow becomes subsonic in this region. The results are consistent with analytical considerations. Density humps, as reported in the literature, are found in conjunction with spiking pulses or prepulses only.
Resolution of K-Splitting in the Rotation-Inversion Raman Spectrum of Ammonia NH3
Authors: Cloppenburg B. , Manczak K. , Prockl H. , Schrötter H. W. , Strey G.
Published: February 2015

The rotation-inversion Raman spectrum of the NH3 molecule has been photoelectrically recorded. The K-splitting in the R-and S-branch could be partly resolved. The intensity contour has been simulated by use of a computer program.
Investigation of T1 and T2 Relaxation for Ethylene Oxide Rotational Transitions
Authors: Mäder H. , Lalowski W. , Schwarz R.
Published: February 2015

The dependence of rotational relaxation times T1 and T2 on pressure and temperature has been determined for various rotational transitions of ethylene oxide by using transient microwave techniques.
Mikrowellen-Spektrum und rotationsspektroskopische Konstanten des 1,3-Dichlorpropins [CH2ClC≡CCl]
Authors: Günther H. , Zeil W.
Published: February 2015

The microwave spectra of three isotopic species of CH2ClC≡CCl were investigated and assigned. We report the rotational constants, centrifugal distortion constants and the nuclear quadrupole coupling constants.
A Molecular Dynamics Study of Aqueous Solutions
Authors: Bopp P. , Dietz W. , Heinzinger K.
Published: February 2015

The central force model for water has been employed in a molecular dynamics simulation of a 2.2 molal NaCl solution. The structural properties of the solution obtained are compared with results of previous simulations where the ST2 model of water was used. Preliminary results on the influence of the ions on the water molecule geometry in the hydration shells are reported. The spectral densities calculated from the hydrogen velocity autocorrelation functions by Fourier transformation indicate differences in the librational and vibrational frequencies between bulk water and hydration water of Na+ and Cl-.
Local States in One-Dimensional Symmetrical Quantum Systems
Authors: Brickmann Jürgen
Published: February 2015

Local quantum states, which play an important role in quantum dynamical treatments, are expanded analytically with respect to a basis of eigen functions of a symmetrical Hamiltonian ℋ̂(x) = ℋ̂(- x). Exact local states (ELS) in one-dimensional symmetrical quantum systems are therein defined as quantum states which are local eigenstates of the Hamiltonian ℋ̂(x) on one half space ℝ+ or ℝ- and are identically equal to zero on the other half space. Local properties like the projection operator on one half space can be given in terms of ELS-basis, but it is shown that the energy moments 〈(〈ℋ̂ 〉 - 〈ℋ̂)k〉 with respect to the ELS do not converge. Consequently, if one uses the ELS as quasistationary initial states, as has been done recently by some authors [5], the lifetimes of these states cannot be estimated from time energy uncertainty relation using the second energy moment as an energy uncertainty measure. A harmonic oscillator system and a symmetrical double oscillator are treated as examples.
Studies of the Chaotic Behaviour in the Peroxidase-Oxidase Reaction
Authors: Olsen Lars F.
Published: February 2015

This note presents experimental results with an enzyme-catalysed reaction with a continuous supply of the substrates in which we observe a transition from periodic behaviour to apparently nonperiodic behaviour by decreasing the enzyme concentration. A model of the reaction is also described. This model, based only on elementary reaction steps, can simulate the periodic behaviour observed experimentally. By changing only one rate constant the behaviour changes from periodic to quasi-periodic behaviour. The work of earlier investigators suggests that such quasiperiodic behaviour (toroidal oscillations) is a step towards chaotic behaviour.
Molekül-und Kristallstrukturen des Dibrom- und Dijodmaleinsäurethioanhydrids Zum Verständnis der Korrelation zwischen / Crystal Structures of Dibrom- and Diiod Maleic Acid Thioanhydride
Authors: Gonschorek Walter
Published: February 2015

The molecular and crystal structures of dibrom maleic acid thioanhydride and diiod maleic acid thioanhydride have been determined by means of single-crystal X-ray intensities. The crystal structures are isomorphous and have the space group P41212 (enantiomorphous with P43212). The lattice constants are a = 7.543 Å, c = 12.155 Å (DBMTA) and a = 7.816 Å, c = 12.348 Å (DIMTA). The five-membered rings of the molecules are planar with maximum deviations of 0.003 Å (DBMTA) and 0.005 Å (DIMTA). Adjacent molecules are held together by van-der-Waals-forces.
Das Bestrahlungsalter und die präatmosphärische Größe des Eisenmeteoriten Unter-Mässing / Cosmic-ray Exposure Age and Pre-atmospheric Size of the Iron Meteorite Unter-Mässing
Authors: Voshage H. , Feldmann H. , Schultz L.
Published: February 2015

The cosmic-ray produced rare gas nuclides and the isotopic composition of potassium have been measured in a sample from the iron meteorite Unter-Mässing. Unusually high concentrations of the rare gas nuclides have been found. Accordingly, an unusually high exposure age of ≈ 1400 Ma was determined by the 41K/40K-method. Unter-Mässing is a meteorite of the chemical group IIC. Thereby, it is the third one found among ≈ 80 meteorites heretofore dated which belongs to one of the sparsely populated side-groups or to no group at all, and at the same time exhibits an extraordinarily high exposure age (anomalous iron Deep Springs: ≈ 2300 Ma, IIIF-Clark County: ≈ 1400 Ma). The experimental data allow, by procedures developed recently, to estimate the pre-atmospheric size of the meteoroid to have been ≈ 2000 kg and the sample investigated to come from a shielding depth of ≈ 16 cm. According to this size estimation. Unter-Mässing cannot be a fragment broken off from the impact projectile of the Nordlinger Ries crater either in the atmosphere at high altitudes or at the explosive impact event.
Energy Transfer in Dye Solutions of Micellar Structure
Authors: Marszałek T. , Baczyński A. , Orzeszko W. , Rozpłoch A.
Published: February 2015

A theoretical description of micellar dye solutions containing donors and acceptors is developed. It is proved experimentally that the luminescent characteristics of Water-Triton X-100 solutions of Coumarine 1 as a donor and Rhodamine 6G as an acceptor are consistent with the proposed theory. It is shown that the probability of energy transfer between dye molecules and the number of detergent molecules in a micelle may be obtained.
Proton Relaxation in Various Copper (II) Complexes and Determination of the Singlet-Triplet Separation
Authors: Jannek H. D. , Midler-Warmuth W.
Published: February 2015

Proton spin-lattice relaxation rates have been measured at 30 MHz as a function of temperature for a large number of dimeric copper complexes with the ligands 8-hydroxyquinoline, pyridine-N-oxide, methyl and dimethyl pyridine-N-oxide, and quinoline-N-oxide. Two carboxylates and adducts of several complexes with various solvents have also been studied. In contrast to some compounds with a normal magnetic behaviour, for most complexes a temperature dependent relaxation has been observed which agrees well with the concept of a weak antiferromagnetic interaction between the two Cu2+ ions. The singlet-triplet separations or exchange integrals have been determined.
The Projectile of the Lappajärvi Impact Crater
Authors: Göbel Elke , Reimold Uwe , Baddenhausen Hildegard , Palme Herbert
Published: February 2015

Two impact melt samples from the Lappajärvi crater (Scandinavia) are highly enriched in siderophile elements, such as Ir, Re, and Os. This indicates the presence of a meteoritic component. The simultaneous enrichments of Ni, Co, Cr, and Se suggest a chondritic projectile. Because of the relatively large indigenous contributions to Ni, Co, and Cr, it is not possible to distinguish between a normal and a carbonaceous chondrite. The high concentrations of relatively volatile elements could point towards a volatile-rich projectile.

The two melt samples have high Re/Ir ratios compared to chondritic ratios. Enrichment of Re relative to Ir is very unusual in terrestrial impact melts. Loss of Re, because of volatilisation under oxidizing conditions or by weathering is frequently observed.

The high Re/Ir ratios and the high abundances of relatively volatile elements either indicate the presence of a volatile rich phase or they characterize a type of meteorite, which has not been sampled. Some lunar highland rocks have a pattern of meteoritic elements rather similar to that observed for the Lappajärvi meteorite.

The Lappajärvi crater is, after Rocheehouart, the second European crater where a significant amount of meteoritic component has been found.

A melt sample from the Lake St. Martin crater (Manitoba), did not show any enrichment in meteoritic elements.
High Energy Radiation-Induced Aggregation of Plasma Proteins. Time Resolved Light Scattering Measurements
Authors: Kihara H. , Schnabel W.
Published: February 2015

Human immunoglobulin (IgG), bovine fibrinogen and bovine serum albumin were irradiated at room temperature with short pulses (50 ns to 2 μs) of 16 MeV electrons in 0.2 M NaClO4 solution containing phosphate buffer (pH 7.5). In the presence of N2O the intensity of light (LSI) scattered by the protein solutions increased after the pulse indicating aggregation. The latter process originates from the attack of protein molecules by OH radicals (aggregation is impeded by t-butanol and augmented by N2O). Upon plotting the relative increase of LSI vs. log time (after the pulse) sigmoidally shaped curves were obtained.

From these findings and results of optical absorption measurements the following is inferred: Aggregation occurs as a consequence of chemical alterations of the protein molecules induced by the attack by OH radicals. The transient species formed during and a few pis after the pulse are reacting within a period of several ms. At the end of this period the formation of aggregates starts. It is concluded that the primary radiation chemical process consists (among others) in the generation of nuclcation sites. The latter subsequently initiate aggregation processes.
63Cu FT-NMR Studies of Tetrahedral Copper(I)-Phosphorus Complexes
Authors: Kroneck Peter , Lutz Otto , Nolle Alfons , Oehler Horst
Published: February 2015

Tetrahedrally coordinated copper(I) complexes CuL4X have been synthesized, L being P(OR)3, PR3 or P(R)n(OR)3-n, and X being a non-coordinating anion such as perchlorate or tetrafluoroborate. Depending on the nature of the bound phosphorus ligand the Cu(I) complexes give well resolved 63Cu NMR spectra including a quintet signal due to spin-spin coupling between 63Cu and 31P. The 63Cu NMR spectra have been analyzed with reference to the chemical shift δ, the shielding constant σ* (given on an absolute atomic scale), the linewidth ⊿v, and the coupling constant J(63Cu-31P). Generally, the relative magnitude of these NMR parameters are in satisfactory agreement with results reported for isoelectronic Ni(O) complexes with the phosphorus ligands mentioned above. Furthermore, the NMR properties of the Cu(I) compounds are discussed in terms of σ-donor or π-acceptor capacities of the ligands coordinated, and stereochemical properties of the complexes.
Wave Propagation in a Moving Cold Magnetized Plasma
Authors: Hebenstreit Helmut
Published: February 2015

Polarization relations and dispersion equations are derived for media electrically anisotropic in the comoving frame. The obtained results are discussed mainly for cold magnetized plasmas, briefly for uniaxial dielectric crystals. Special directions of wave propagation are considered.
Ermittlung der Elektronenaffinitäten von Maleinsäureanhydrid, -thioanhydrid, -imid und einiger ihrer disubstituierten Halogen- derivate über CT-Messungen und ihre semiempirische Berechnung (MINDO/3)
Authors: Fleischhauer Jörg , Asaad Adel N.
Published: February 2015

Using Mulliken’s theory of intermolecular interactions the electron affinities of some cyclic olefines (electron acceptors) have been determined by measurement of the charge transfer energies of their complexes with the electron donors 2,5-dimethyl-2,4-hexadiene and hexamethylbenzene. These electron affinities are compared with MINDO/3-results. It is investigated whether a correlation of the experimental affinities and the calculated π-HOMO-energies is possible. Finally the expected dienophilicities of the olefines are discussed.
Formation of BrO2 in the Belousov-Zhabotinsky-System- Investigation of the Ce3+ /BrO3
--Reaction*
Authors: Försterling H.-D. , Lamberz H. , Schreiber H.
Published: February 2015

The reaction between Ce3+ and bromate was studied in sulfuric acid solution using a dual wavelength spectrometer. From the spectral dependence of the absorbance in the region from 450 to 600 nm it is concluded that BrO2 is an intermediate of the reaction. The kinetics of formation and decay of BrO2 is compared to theoretical models.
High Temperature Behaviour of Positrons in Argon
Authors: Grover P. S.
Published: February 2015

The annihilation decay rates and average energy of positrons in argon gas have been calculated using the Boltzmann diffusion equation formalism at high temperatures as a function of electric fields. A comparison is made between the theoretical and experimental results. The agreement obtained is quite reasonable.
Notizen:Eichfeldtheorie zur U3-invarianten Pais-Gleichung/ Gauge Field Theory of an U3-invariant Pais Equation
Authors: Bopp Fritz
Published: February 2015

We are looking for the gauge field theory which corresponds to the U3-invariance of the recently obtained free particle Dirac equation generalized according to an idea of Pais.
Seven Shock-transformed Hexahedrites, Sensitive to Grainboundary Corrosion
Authors: Buchwald V. F.
Published: February 2015

Seven polycrystalline iron meteorites (Forsyth County, Holland's Store, Wathena, Pima Co., Chico Mountains, Kopjes Vlei and Mejillones), of bulk composition as normal hexahedrites of group II A, are shown to be severely altered hexahedrites. Mic-roprobe examination and various heat treatments of synthetic alloys support the conclusion that the meteorites after a primary slow cooling were subjected to shock-reheating above 800°C. Thereby the following transformations took place a-α-γ->α2->α, and an unequilibrated structure, very sensitive to grain-boundary corrosion was formed.
Laserspectroscopic Investigations in the Configuration 5d6s6p of Lu I
Authors: Kwiatkowski M. , Teppner U. , Zimmermann P.
Published: February 2015

In an atomic beam of Lu, six levels of the configuration 5d 6s 6p in the energy range 18000 to 23000 cm-1 were selectively populated with the light of a pulsed dye laser. Time resolved observation of the recmitted resonance light was used to deduce the lifetimes of the excited levels.
Correlation Between Structure and Phonon Spectra of Linear Polyiodide Chains in Tl6I6M2/n
n+(I4)2-, [M = Pb, Ag, Au, (Bi0.5 Tl0. 5)]
Authors: Stolz H. J. , Trageser G.
Published: February 2015

Raman-and IR-spectra of four compounds of the general composition Tl6I6M2/n
n+(I4) [n: formal valence of the M-atom, M = Ag, Au, Pb and (Bi0.5Tl0.5)] were investigated in order to identify the polyiodide species present. In accordance with structural results comparable amounts of I4
2-and I3
-/I--groups were found for M = Ag, Pb and (Bi0.5Tl0.5), while in Tl6I6Au2(I4) I3
-/I--groups predominate.
Über das magnetische Verhalten von Cs2MHoF6 (M = Na, K, Rb)
Authors: Urland W.
Published: February 2015

The magnetic behaviour of CS2MHoF6 (M = Na, K, Rb) has been studied in the temperature range between 3.2 and 251.3 K. The magnetic data are interpreted by means of a previously developed model in which the influence of the crystal field is theoretically described by the angular overlap model. Values of the angular overlap parameters eσ(R) and eπ(R) cannot be determined unequivocally. The energy values of the crystal-field levels of the 5I8 ground state are calculated.
Diffusion Coefficients of Rb+ and Cs+ Ions in Molten Nitrate Systems
Authors: Odawara O. , Kwak Jan C. T. , Ketelaar J. A. A.
Published: February 2015

The tracer diffusion coefficients of 86Rb and 137Cs ions in the molten (Li-Na)NO3, (Li-K)NO3, (Li-Rb)NO3, and (Li-Cs)NO3 systems have been measured by means of a paper strip method. Results from the paper strip method in some pure nitrates are compared with the results from capillary and optical interferometric methods. With increasing concentration of LiNO3, the diffusion coefficients at 350°C are found to decrease in the (Li-Na)NO3 system and to increase in the (Li-K)NO3, (Li-Rb)NO3, and (Li-Cs)NO3 systems. For 86 Rb in (Li-K)NO3 an increase is followed by a decrease. These findings are discussed by taking into consideration the free space in the solvent system and the ionic interaction between the diffusing and the surrounding ions.
When do Projections Commute?
Authors: Rehder W.
Published: February 2015

Necessary and sufficient conditions for commutativity of two projections in Hilbert space are given through properties of so-called conditional connectives which are derived from the conditional probability operator PQP. This approach unifies most of the known proofs, provides a few new criteria, and permits certain suggestive interpretations for compound properties of quantum-mechanical systems.
Microwave Spectrum of Ethyl Iodid: Internal Rotation Analysis
Authors: Boucher D. , Dubrulle A. , Demaison J.
Published: February 2015

The rotational spectra of the first excited state of the methyl torsion and the CCI-in plane deformation of CH3CH2I have been studied. A Coriolis interaction between these two modes has been found. Splittings of transitions in the first excited torsional state show that the barrier hindering internal rotation of the methyl group is 3.62 kcal/mole. This value agrees quite well with the value previously reported from Raman studies. It is internally consistent and similar to the other ethyl halides.
Anisotrope Fluoreszenz langgestreckter Moleküle in Lösungsmitteln unterschiedlicher Viskosität
Authors: Kawski A. , Kukielski J. , Bałuk P. , Lenczewska M.
Published: February 2015

The emission anisotropics (r) of the fluorescence of the prolate molecules (whose emission transition moments are parallel to the long axis) 4-dimethylamino-4'-cyanostilbene, 4-methoxy-4'-nitrostilbene, 4-dimethylamino-4'-diphenylphosphinoxidstilbene, 4-dimethylamino-4'-bromstilbene and pbis[ 2- (5-α-naphthyloxazolyl) ] -benzene in solvents of different viscosities {η) have been studied. Also for these substances the non-linear dependence of 1/r on T/η was confirmed. This non-linearity in the low viscosity range can be explained by the assumption that the prolate luminescent molecules perform irregular rotational motions within a solid angle smaller than 90°. Effective volumes and rotational relaxation times for the different molecules in the different solvents were obtained.
ESR-Untersuchungen an antiferromagnetischem CrN zum Einfluß der Temperatur auf die Austausch-Wechselwirkung / ESR-Investigation on Antiferromagnetic CrN Concerning the Influence of Temperature on the Exchange-Interaction
Authors: Dräger K. , Gerling R.
Published: February 2015

The ESR-behaviour of antiferromagnetic and almost stoechiometric CrN is thoroughly investigated above its Neél-point. For polycrystalline samples a spectroscopic splitting factor g =1.965 and a differential line width ⊿B = 56,7 mT is measured at room temperature. All resonance lines exhibit Lorentzian character to a high degree.

In the temperature range between 300 K and 520 K the ESR-intensity can satisfactorily be described by a model of local ordering. Its binding energy is computed to be about ⊿E = 500 ± 20 cm-1. A more refined analysis shows a systematic change of ⊿E with temperature and a discrepancy between the Neel-point TN and the temperature Ts characterizing a singular behaviour of the line width ⊿B. Apart from these deviations originating in a magnetic ordering of the fourth kind, the cluster-model gives an isotropic exchange between next nearest neighbours of J2 = -33.2 cm-1. This result is confirmed by molecular field computations.
A Molecular Dynamics Simulation of Molten (Li-Rb)Cl Implying the Chemla Effect of Mobilities
Authors: Okada Isao , Takagi Ryuzo , Kawamura Kazutaka
Published: February 2015

A new transport property, the self-exchange velocity (SEV) of neighbouring unlike ions, has been evaluated from molecular dynamics simulations of molten LiCl, RbCl and LiRbCl2 at 1100 K and the mixture at 750 K. From the increase of the SEV's in the order Rb+ (pure salt) <Li+ (mixture) < Rb+ (mixture) < Li+ (pure salt), it is conjectured that there is a strong correlation between the SEV’s and the internal mobilities. An interpretation of the Chemla effect in its dependence on temperature is given. The pair correlation functions and the self-diffusion coefficients are also calculated and discussed.
Molybdates Solid State Synthesis: The MgO—MoO3 System
Authors: Massarotti V. , Flor G. , Marini A. , Riccardi R.
Published: February 2015

The formation reaction of Mg2Mo3O11 from MgO (single crystal) and MoO3 (pellet) has been investigated in the temperature range 873-973 K.

Supported by an analysis of the transport properties a mechanism is proposed involving a unidirectional transport of Mo6+ via V6′
Mo and of oxygen via gas phase.

The transport properties of MgMoO4 (the other intermediate compound in the system MgO-MoO3) were also studied and the results were found to agree with the mechanism observed in a previous work on the basis of kinetic and structural considerations.
Selectivity in Ketenimine Cycloadditions. Photoelectron Hel Spectra of Ketenimines
Authors: Bernardi Fernando , Bottoni Andrea , Ballaglia Arturo , Distefano Giuseppe , Dondoni Alessandro
Published: February 2015

The first few bands in the photoelectron (Hel) spectra of ketenimines R1R2C-C=NR3(R1,R2=H, CH3, C5H6, CH2=CH; R3=alkyl or aryl group) are assigned to the corresponding molecular orbitals. The assignment is based on SCF-MO calculations made at three different levels (CNDO/2, ab-initio STO-3C and 4-31G) coupled with perturbational molecular orbital analyses.

The π-orbitals of the unsaturated substituents are found to interact with one of the two perpendicular π-electron systems of the〉C=C=N- residue, the critical factor being the position of attack of the substituent.

The relevance of these results on the site selectivity observed in cycloaddition reactions of these species is discussed.
Patterns of Spatial Organization in Growth
Authors: Marek Miloš , Kubíček Milan
Published: February 2015

Patterns of spatial concentration profiles arising in one-dimensional reaction-diffusion systems in the course of variations of the characteristic dimension of the system (growth) are analyzed. The spatial profiles established and their changes depend on the character of the steady state pattern dependence on length. If the families of solutions (spatial profiles) arising at L = nL1*, nL2* form closed curves, and a slow (quasistationary) linear or exponential increase of the characteristic dimension is considered, then subsequently more complex patterns of spatial concentration profiles appear regularly in a reproducible way. The system keeps every established pattern for a fixed interval of time which depends on the rate of growth. Implications for two different interpretations of the morphogen gradient formation in the models of embryogenesis are discused.
Unified Theory of Electrons and Photons in Heavy Ion Collisions
Authors: Kirsch Johannes
Published: February 2015

We present a unified formulation of the interaction of electrons with the electromagnetic field in heavy ion collisions, based on quantized interacting fields. This reduces the effort in treating many-electron systems substantially, as compared with the usual S-matrix theory. Both formalisms are shown to be equivalent. The simplification achieved by our new approach is demonstrated in detail for the example of quasi-molecular radiation
Direct X-Ray Study of the Molecular Tilt in Dipalmitoyl Lecithin Bilayers
Authors: Hentschel M. , Hosemann R. , Helfrich W.
Published: February 2015

Direction and angle of molecular tilt in an ordered multilayer system of dipalmitoyl lecithin and water were directly determined by X-ray diffraction as a function of temperature in the gel phase with ca. 20 wt. % of water
Hydrogen Stark Broadening by Different Kinds of Model Microfields
Authors: Seidel Joachim
Published: February 2015

The “method of model microfields (MMM)”, which has been employed successfully especially for the calculation of hydrogen Stark profiles, is based on the assumption that reliable line shapes may be obtained from just the probability density of the plasma microfield and its autocorrelation function. To test the influence of higher order statistical features two different model microfields have been used to investigate Stark broadening of hydrogen Lyman lines by either electrons or ions. Corresponding profiles computed in this way lie close together over the full intensity range, but systematic relative deviations of about 20% show up at frequency separations from the unperturbed line of approximately three times the plasma frequency (for electrons or ions, respectively), i.e., in the “transition region” where neither the impact nor the static approximation holds. Though the joint action of electrons and ions as well as Doppler broadening will tend to diminish these deviations, the present form of the MMM cannot be expected to yield an accuracy better than some 10% throughout the line profile.
Diode Laser Spectrum of HCCCN near 5 μm
Authors: Yamada Koichi , Schieder R. , Winnewisser G. , Mantz A. W.
Published: February 2015

The ν3 vibration-rotation band of cyanoacetylene, HC3N, has been measured in the wavenumber range 2068 to 2095 cm-1 to an accuracy of better than ± 0.005 cm-1 using a diode laser spectrometer. The width of the observed lines is essentially limited by Doppler-broadening. The band center of the ν3 vibration is determined from the observed P- and R-branch transitions to be at 2079.30500 (58) cm-1. The rotational constant of the excited state is B′= 0.151212 (10) cm-1.
Investigation of Transient Dispersion and Absorption Phenomena with a Bridge Type Superheterodyne Microwave Spectrometer
Authors: Bomsdorf H. , Dreizler H. , Mäder H.
Published: February 2015

A bridge type superhet spectrometer for time resolved investigation of rotational relaxation is described. Allowing the application of both Stark- and pump-modulation techniques the arrangement may be used for single and double resonance experiments, showing a lot of advantages compared with a conventional Stark- or double resonance-spectrometer. These features are discussed in detail.

By means of a MW-pulse method the following two-level experiments have been carried out. The rotational relaxation time T2 was measured by detection of M-unresolved transient emission signals for J = 1 - 2 of 16O12C32S, 16O12C34S and 16O13C32S in natural isotopic abundance and for eight transitions of SO2 up to J = 43. The signals of transient dispersion were detected and compared with those of transient absorption. Their theoretical description in terms of the two-level Bloch equations is discussed.
A Topological Approach to the Calculation of the n-Electron Energy and Energy Gap of Infinite Conjugated Polymers a
Authors: Bonchev D. , Mekenyan O.
Published: February 2015

A procedure was developed, on the basis of the distance matrix of the graph, for the calculation of the specific π-electron energy and energy gap in polymerhomologous series and infinite polymers. 25 conjugated polymers were examined by this procedure and a fairly good correlation between these energy characteristics and the sum of all distances in the graph (the Wiener index) was found. A zero energy gap was shown to occur in 12 polymers. For polymers composed of condensed benzenoid and non-benzenoid cycles, a linear correlation was found between the Wiener index normalized to infinite polymer chains and the specific π-electron energy thus revealing possibilities for predictions proceeding from monomer topology only.
On the Thermal Behaviour of the n.C13— n.C20 Potassium Alkanoates
Authors: Cingolani A. , Spinolo G. , Sanesi M. , Franzosini P.
Published: February 2015

A DSC study, supplemented by X-ray diffraction measurements, was carried out on potassium soaps from n.tridecanoate to n.eicosanoate in the range between room temperature and the isotropic liquid region. The present results are combined with earlier ones for the shorter homologues down to methanoate to draw a rather comprehensive picture of the phase relationships concerned. The significant features shown for a number of transition series by plots ΔS vs the number of carbon atoms, as well as the dimorphism exhibited by tridecanoate at room temperature are also discussed.
Shift of the Til 535.0 nm line by hydrogen
Authors: Lisicki E.
Published: February 2015

The shift by hydrogen of the 535.0 nm T1 line resulting from photodissociation of thallium iodide was investigated at low densities. A linear variation of the shift with the hydrogen density was found with a shift coefficient of -(0.443 ± 0.012) X 10-20 cm-1 /(molecules cm-3).
Singlett-Singlett-Energieübertragung im System 5-Acetyl-5H-benzo[b]carbazol/5H-Benzo[b]carbazol
Authors: Zander M.
Published: February 2015

Efficient singlet-singlet energy transfer from 5-acetyl- 5 H-benzo[b] carbazole (donor) to 5 H-benzo[b] carbazole (acceptor) takes place in methylcyclohexane/isopentane as an inert matrix at 77 K. The energy transfer is shown to occur in microcrystals of the donor containing small amounts of the acceptor. Both sensitized prompt and Ptype delayed fluorescence of the acceptor is observed. The fluorescence behaviour of the micorcrystaline phase is compared with that of mixed crystals obtained from the melt.
Unification of Brueckner Theory and HFB Theory
Authors: Gerstenmaier Y. , Schütte D.
Published: February 2015

A cluster expansion for the expectation value of operators with correlated wave functions is presented. A variational approach to the Brueckner theory with occupation probabilities is generalized and HFB theory incorporated.
Proof of Kruszewski's Rule
Authors: Gutman Ivan
Published: February 2015

A rule for the stability of isomeric polycyclic conjugated compounds, which was recently formulated by Kruszewski [1], is proved.
Die spezifische Verbreiterung der FeI-Resonanzlinie 3859,91 Å durch Stöße mit Argonatomen bei hohen Temperaturen / Specific Line-Broadening of the Iron-Resonance-Line 3859,91 Å by Collisions with Argon Atoms at high Temperatures
Authors: Steinwandel J. , Joos V. E. , Hauser M. , Dietz Th.
Published: February 2015

The specific line-broadening cross section of the FeI-resonance transition at 3859.91 Å by collision with argon atoms was measured in the temperature range of 2000 K ≦ T ≦ 3500 K in a shock tube.

Driving gas was Helium, shock wave carrier gas and collision partner was Argon. The free iron atoms were produced by the unimolecular decomposition of ironpentacarbonyl in the front of the incident shock wave.

The initially produced iron condensate evaporates completely in the reflected shock wave to form free atoms. They are present behind the reflected shock wave in the form of a thermodynamically well defined undersaturated vapour. Thermodynamic quantities of the vapour do not change during the observation time.

The line-broadening cross section σL(T) was measured by the method of integral atomic line absorption spectroscopy on the FeI-resonance line at 3859.91 Å to (10.05 ± 1.40) x 10-15 cm2 . Temperature variations in σL are smaller than experimental errors.
1,2,4-Triazole Complexes XII * . Magnetic properties of Fe (1, 2, 4-triazole)2 (NCS)2, a quasi two-dimensional S = ½. antiferromagnet with hidden canting.
Authors: Engelfriet D. W. , Groeneveld W. L. , Nap G. M.
Published: February 2015

Fe(trz)2(NCS)2 has been investigated by means of magnetic susceptibility and magnetization measurements on single crystals at temperatures 1.8-300 K, heat capacity measurements at 1.5-90 K and neutron powder diffraction at 1.2 K. The compound orders antiferromagnetically at Tc = 8.46(2) K. The susceptibilities along the orthorhombic axes are strongly anisotropic, the a axis being the preferred direction. The susceptibility data along a and the heat capacity results are in reasonable agreement with the predictions for the quadratic layer, S = ½. Ising antiferromagnet, with an intralayer exchange constant J/k = - 7.2(2) K. Below Tc the magnetization curve along the a axis reveals a metamagnetic transition at 1.74 kOe. In accordance with the Ising-like properties, a direct transition from the antiferromagnetic to the paramagnetic state is observed along a at 50 kOe.

Hidden canting is found to be present. At 1.2 K the compound appears to be monoclinically distorted with α = 88.3° (with respect to Aba2, the space group at 300 K). The magnetic structure consists probably of four sublattices with the magnetic moments lying in the planes z = 0 and z =½ (with respect to the distorted cell in Aba2) along directions that are at an angle of 8° with the a axis.

Ligand bonding parameters are discussed in terms of the angular overlap model.
Untersuchungen zur Anwendbarkeit des CNDO/S-CI-Verfahrens für die Berechnung der Anregungsenergien organischer Verbindungen am Beispiel von Phthalsäurederivaten / Investigations on the Applicability of the CNDO/S-CI method for the Calculation of Excitation energies of Organic compounds using Derivatives of Phthalic acid as Examples
Authors: Fabian Walter
Published: February 2015

The influence of the choice of geometrical parameters and the approximations used to evaluate the two centre coulombic integrals upon excitation energies as calculated by the CNDO/S-or INDO/S-CI method is discussed.
Influence of Doping on the Crystal Potential of Silicon investigated by the Convergent Beam Electron Diffraction Technique
Authors: Voss R. , Lehmpfuhl G. , Smith P. J.
Published: February 2015

Low index structure potentials of silicon were determined by convergent beam electron diffraction (Kossel-Möllenstedt technique) from very small crystal areas of about 100 Å in diameter. The values of 111, 222, 220, 113 and 004, determined to an accuracy of ±0.03 volts, are in excellent agreement with the accurate X-ray results of Aldred and Hart (see [6], p. 239). Heavy arsenic or phosphorous doping was found to cause a shift of 0.15 volts in the 111 structure potential. Absorption potentials were also determined and found to be 1/3 of the theoretical values published by Radi [20].
Structure and Packing Density of Liquid Metals
Authors: Steffen B. , Hosemann R.
Published: February 2015

Recent results concerning the structure of microparacrystals established in different melts are reported. In spite of structural differences among the investigated samples the reduced density is always the same. This approach is possibly a first step towards a correlation between the hard sphere concept of statistical mechanics and our refined structural analysis.
Convergence Problems and Energetic Regions in π Excited States of Certain Conjugated Molecules
Authors: Giambiagi Myriam S. de , Giambiagi Mario , Barros Henrique G. P. Lins de
Published: February 2015

When calculating π bond orders of excited and superexcited states of conjugated molecules, difficulties arise in applying the variation method; besides, the convergence problems involved are well known. For pyridazine, chosen for discussion, 27 states are considered; the convergence problem is envisaged through two criteria in the choice of a parameter introduced in the compromise Hamiltonian. This convergence parameter is related to the variation method. There exist three particular solutions for bond orders, which divide the 27 states into energetical regions.
On the Measurement of Elastic Constants in Nematic Liquid Crystals: Comparison of Different Methods
Authors: Gerber Paul R. , Schadt Martin
Published: February 2015

Different methods of measuring elastic constants of nematic liquid crystals by deformation of homogeneously and homeotropically oriented layers through external magnetic and electric fields, respectively, are critically examined. Possible sources of uncertainties are quantitatively explored. An approximative numerical fitting procedure is proposed allowing to take conductivity effects in electrically deformed layers up to large conductivities and/or temperatures into account. A novel, accurate and simple monitoring method to determine twist elastic constants is described. The measurements of the temperature dependence of the splay bend and twist elastic constants of the positive dielectric mixture R0-TN-403 are presented.
Unrestricted Harmonic Balance
Authors: Seelig Friedrich Franz
Published: February 2015

Periodic structures in chemical kinetic systems can be evaluated by an extension of the well-known method of harmonic balance, which yields very simple expressions in the case of linear systems containing only zero and first order reactions. The far more interesting non-linear systems containing e.g. second order reactions which in case of open systems far from thermodynamic equilibrium give rise to non-classical phenomena like oscillations, chemical waves, excitability, hysteresis, multistability, dissipative structures etc. can be treated in a similar way by introducing new pseudo-linear quantities utilizing certain group properties of harmonic expansions. The resulting complicated implicit non-linear algebraic equations are solved by a method developed by Powell and show good convergence. Since this method - in contrast to the conventional method of simulation - is independent from the stability of the periodic structure to be evaluated it can even be applied to unstable cases where the simulation method necessarily fails. An evaluation of the stability is included in the developed computer program.
Equilibrium Positron Decay Rates in Helium
Authors: Grover P. S. , Muhammed M. S. A. , Sami S. A.
Published: February 2015

Equilibrium positron decay rates in helium gas have been computed over a wide range of temperatures and electric fields based on the model due to McEachran et al. [7]. Agreement between the theoretical and experimental values of the decay rate at room temperature and zero electric field is quite good.
Mass Spectrometry of Polymers: Polypropylene Glycol
Authors: Neumann Gregory M. , Cullis Peter G. , Derrick Peter J.
Published: February 2015

Mass spectra have been measured, using the field desorption technique, for polypropylene glycols with nominal mass-average relative molecular masses of 1000, 2000, 3000 and 4000. Ions of up to m/z 7400 have been observed. Major peaks in the spectra correspond to (M + H)+ ions. (M + Na)+ ions are observed if sodium iodide is added to the sample. There are strong peaks corresponding to fragmentation of the polymer chains close to their termini. It is suggested that these fragmentations are induced by the strong electric fields at the emitter.
The Kinetics of Plastic Flow
Authors: Faucher B. , Krausz A. S.
Published: February 2015

The plastic flow associated with the three main methods of combining deformation mechanisms is described in terms of deformation kinetics. It is shown that the determination of the deformation kinetics as the initial step in the analysis is indispensable to the establishment of the activation parameters in functional forms. To this purpose, the effects of stress and temperature on the plastic strain rate are determined for three types of combined mechanisms, and qualitative comparison with experimental results is presented.
Temperature Coefficient of the Refractive Index of H2O and D2O and Proposed Models of Water Structure
Authors: Abbate G. , Bernini U. , Ragozzino E. , Somma F.
Published: February 2015

The temperature coefficient of the refractive index, (∂n/∂T)p, has been measured for deuterium oxide. The observed values are considered together with those previously obtained for water. The experimental data cannot be explained with the best known models of molecular polarizability, at least in the approximation generally used in these models. Therfore they are discussed on the basis of a different approximation, suggested by a well-known structural model of liquid water. It is shown that the experimental results are very well explained, in a wide range of temperature, with the hypothesis of the existence of "structural voids".
Thionine Fluorescence Quenching by Metal Cations
Authors: Köhler G. , Solar S. , Getoff N.
Published: February 2015

The mechanism of the fluorescence quenching of aqueous thionine by various metal ions (Ce3+, Fe2+, Mn2+, Mg2+, Cs+ and Na+) was studied at pH = 2.5. The following Stern-Volmer constants (Ksv) were determined: KSV(Fe2+) == 1.13 dm3 mol-1, KSV(Mn2+) = 0.24 dm3 mol-1, KSV(Ce3+) = 0.24 dm3 mol-1, KSV(Cs+) - 0.03 dm3 mol-1. At concentrations below 1 mol.dm-3 Na2SO4 and MgSO4 are very weak quenchers (KSV(Na+ or Mg2+) = 0.007), but the influence on the fluorescence yield increases considerably at higher cation concentrations. This was attributed to the formation of ground state complexes between thionine and SO4
2- ions. The salt concentration affects considerably the quenching rate of Fe2+ ions, but much less so that of the other cations. Fluorescence quenching mechanisms are discussed.
Experimental Observation of Chaotic Behavior in CO Oxidation in Lumped and Distributed Catalytic Systems
Authors: Rathouský J. , Puszynski J. , Hlaváček V.
Published: February 2015

Measurements of the catalyst temperature and outlet conversion in differential, integral and honeycomb systems give evidence that the catalytic CO oxidation may proceed chaotically in time over a range of inlet CO concentrations and temperatures. Development of aperiodic oscillations from periodic oscillations was experimentally investigated. In distributed systems chaotic behavior may exist only in a narrow range of inlet temperatures.
Zur Bildung von Mg2Si- und CaSi2-Schichten auf einkristallinen Siliciumsubstraten
Authors: Braungart R. , Sigmund H.
Published: February 2015

Thin layers of Mg2Si or CaSi2 (10-20 μm) on silicon substrates can be prepared by the reaction of the corresponding metal vapor with silicon wafers. The resulting poly crystal line silicides have a purity of more than 99.95%; their surface roughness is about 2 μm. The layer thickness and the dimensions of the crystallites may be controlled by the conditions of the preparation. An oriented growth on the <111>-silicon surface is observed in the case of CaSi2- The method described seems generally well suited for growing silicide layers of metals with high vapor pressure. The Mg2Si- and the CaSi2-layers were used as starting material in a special "sandwich"-epitaxy in order to prepare Mg- and Ca-doped Si-layers.
Evidence for Triplet Exciplex Formation in the Reaction of Amines with 1 -Pheny l-2-acetoxy-2-methy 1-propanone-1
Authors: Salmassi A. , Eichler J. , Herz C. P. , Schnabel W.
Published: February 2015

1-Phenyl-2-acetoxy-2-methylpropanone-1 has been irradiated with 25ns flashes of 347 nm light in benzene or cyclohexane solution. Absorption measurements yielded the following: at the end of the flash the triplet-triplet spectrum was observed (triplet decay rate constant: kT = (3.0 ±0.2) 105 s-1). In the presence of aliphatic amines (e.g. triethanol amine) radicals were formed much more slowly than triplets disappeared, as clearly indicated by spectral changes at wave lengths between 330 and 380 nm. The radical precursor thus evidenced is presumed to be an exciplex. Rate constants: kT + amine: (1.2 + 0.2) 109 l/mol s; kexciplex: (9± 1) 106 s-1 .
Zur approximativen Lösung der Einelektronen-Schrödinger-Gleichung mit Hilfe eines Differenzen-Hamilton-Operators demonstriert am Beispiel des H-Atoms in einer sphärischen Box
Authors: Fleischhauer Jörg , Gerlach Eckard
Published: February 2015

For an H-atom in a spherical box with variable radii R it is shown that the energy and the ESR-splitting constant for the groundstate calculated with a difference-hamiltonian are in good agreement with the results obtained by other methods. The dependence of the energy on the number n of discrete points and their distance for a given radius R is considered.
Electron-Nuclear Hyperfine Interactions of 53Cr 3+ in Mg2SiO4 (Forsterite)
Authors: Rager H.
Published: February 2015

The magnetic hyperfine interaction between the electron and nuclear spin system of 53Cr3+ was studied at the Mg sites, M1 and M2, in Mg2SiO4. The study was undertaken at room temperature and 9.52 GHz. The hyperfine structure data exhibit a covalent Cr-O bonding of approximately 10% indicating a mainly but not purely ionic bonding. Including the corresponding results obtained for 57Fe 3+ [1] and 55Mn2+ [2] in Mg2SiO4, this is interpreted such that the bonding of transition metal ions is mainly dominated by the oxygen sublattice in Mg2SiO4 and less by the properties of the transition metal ions themselves. The small variation of the hyperfine splitting parameters found for 53Cr3+ at M1 and M2, and also for 57Fe3+ at these positions indicates that the hyperfine interaction varies also with varying average metal oxygen distances as well as with changes in the oxygen coordination size.
Temperature Dependence of the 72P States Mixing and Quenching in Caesium-Deuterium Collisions
Authors: Łukaszewicz Marek
Published: February 2015

Temperature dependent mixing and effective quenching cross-sections for the 72P doublet in caesium, induced in collisons with molecular deuterium, were determined experimentally using the sensitized fluorescence method. The character of the temperature dependence exhibits an isotope effect compared to the data for caesium-hydrogen collisions obtained earlier.