bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection of Ar-CH4 Complexes in the 7μm Region by Diode Laser Spectroscopy
Authors: Pak I. , Hepp M. , Roth D.A. , Winnewisser G. , Yamada K.M.T. 
Published: February 2015

Abstract
The absorption spectrum of the Ar-CH4 van der Waals complex was measured for the first time in the 7 μm region. The complexes were produced in a pulsed slit supersonic jet and detected by a tunable diode laser spectrometer with 40 MHz spectral resolution. The strongest absorption features of the Ar-CH4 complex were observed in the spectral region 1310.57-1311.05 cm -1 , located between the Q(l) and the R(0) lines of the ν4 fundamental band of the methane monomer. It was found that the newly detected absorption lines belong to three Q-branches of the Ar-CH4 complex. The transitions of these Q-branches are related to the Q(l) transition in the ν4 fundamental band of the methane molecule, which can rotate almost freely inside the complex. The three Q-branches have been assigned.
Dielectric Studies of a Series of Liquid Crystalline Pyridine Derivates
Authors: Heinemann S. , Kresse H. , Saito S. , Demus D. 
Published: February 2015

Abstract
Measurements of the temperature and frequency dependence of dielectric constants have been performed for five homologues in the range 100 Hz -10 MHz. These substances exhibit a negative anisotropy of the dielectric constants and two relaxation regions (rotation of the molecules around the short resp. long axis) in the investigated frequency range. Even in the crystalline state dipolar reorientations are possible which have been interpreted as rotations of the alkoxy group. Changes of the static dielectric constants, relaxation frequencies and transition entropies are discussed as a measure of structural changes passing the several liquid crystalline phases.
Isolated versus Condensed Anion Structure: the Influence of the Cation Size and Hydrogen Bond on Structure and Phase Transition in MX4
2- Complex Salts. 2,2-Dimethyl-1,3-propanediammonium Tetrabromocadmate(II) Monohydrate, Dimethylammonium Tetrabromozincate(II), and Dimethylammonium Tetrabromocadmate(II)
Authors: Ishihara Hideta , Dou Shi-qi , Horiuchi Keizo , Krishnan V. G . , Paulus Helmut , Fuess Hartmut , Weiss Alarich 
Published: February 2015

Abstract
In the course of work on the anion condensation of Cd and Zn halides, the crystal structures and 79,81 Br NQR spectra of 2,2-dimethyl-1,3-propanediammonium tetrabromocadmate(II) monohydrate (1) and dimethylammonium tetrabromozincate(II) (2), and 79-81 Br NQR spectra of dimethyl-ammonium tetrabromocadmate(II) (3) have been studied. An isolated [CdBr4]2- ion of the salt [H3NCH2C(CH3)2CH2NH3 ]CdBr4 • H2O (1) is formed, with polar orthorhombic space group Pbc21, Z = 4, a = 645.5(3), b = 1628.3(8), c -1389.5(6) pm. [(CH3)2 NH2 ]2ZnBr4 (2) has also an isolated anion lattice, with monoclinic space group, P21 /c, Z = 4, a = 870.6(3), b = 1195.6(4), c = 1628.9(5) pm, β = 121.84(1)°. The 81 Br NQR spectrum of (1) is a quartet (ν in MHz, T = 77 K/ 303 K): ν1 = 68.403/64.278; ν2 = 65.296/62.663; ν3 = 56.525/54.660; V4 = 43.211/45.422. The 81 Br NQR spectrum of (2) is a quartet too (ν in MHz, T= 77 K/300 K): ν1 = 66.848/64.784; ν2= 63.152/ 61.883; ν3 = 57.498/55.890; ν4 = 49.416/50.224. The 81 Br NQR spectrum of [(CH3)2NH2 ]2CdBr4 (3) is also a quartet (ν in MHz, T =77 K/310 K): ν1 = 68.606/67.272; ν2 = 65.806/63.296; ν3 = 58.096/ 57.369; ν4 = 55.757/53.393. The change of NQR frequencies with temperature is smooth for all three compounds. One of the 81 Br NQR lines in both (1) and (2) increases slightly in frequency with increasing T. In the compound (1), the H2O coordinates to NH3
+ groups and to bromines forming a distorted tetrahedron (Br...)2 ...H2O... (... HN)2 , the six angles lying between 69° and 131°. The relations between the bromine NQR and the crystal structures are discussed for the title compounds.
Photoselection of Luminescent Molecules in Anisotropic Media in the Case of Two-Photon Excitation. Part II. Experimental Studies of Hoechst 33342 in Stretched Polyvinyl alcohol) Films
Authors: Kawski A. , Gryczyński Z. , Gryczyński I. , Lakowicz J. R. , Piszczek G. 
Published: February 2015

Abstract
It was found by investigating dichroism and emission anisotropy in the case of one-and two-photon excitation of Hoechst 33342 [bis-benzimide,2,5'-bi-1H-benzimidazole, 2'-(4-ethoxyphenyl)-5-5(4-methyl-1-piperazinyl)] in stretched poly(vinyl alcohol) (PVA) films, that the absorption and fluorescence transition moments lie along the long molecular axis of the molecule studied. The slight deviation of the transition moment direction in fluorescence (about 8°) from that in absorption can be due to the incomplete linearity of the Hoechst molecule.
Notiz: The Dependence of Vicinal Proton-Proton Coupling Constants of Norbomenes on Molecular Structure
Authors: Marković Zoran , Konstantinović Stanimir , Gutman Ivan 
Published: February 2015

Abstract
A modification of the Karplus equation, containing four mutually independent structural terms and five adjustable parameters, is put forward. The new structural factor, introduced into this modification is sin (θ1 + θ2)/2. The new equation reproduces experimental NMR vicinal coupling constants of norbornenes with a standard deviation of about 0.45 Hz.
Monte Carlo Simulation of the Director Field of a Nematic Liquid Crystal with Three Elastic Coefficients
Authors: Gruhn T. , Hess S. 
Published: February 2015

Abstract
In this article, a Monte Carlo simulation is presented, which generates the equilibrium director field of a nematic liquid crystal under the influence of an external field and fixed boundary conditions. The liquid crystal is characterized by a set of directors on a spatially fixed lattice. The simulation is based on an expression for the Frank free energy with three elastic coefficients. The chosen discretisation conserves the nematic symmetry, which means n and - n are equivalent. The results for several Frederiks geometries with homogeneous and spatially modulated external fields are shown, as well as an investigation of a capillary with homeotropic boundary conditions. Further we compare our method with the Lebwohl-Lasher model and introduce an extension of the latter which distinguishes between splay-, twist-and bend-configurations.
Effect of a Tangential Electric Field on the Second Harmonic Resonance in Kelvin-Helmholtz Flow
Authors: Singla R. K. , Chhabra R. K. , Trehan S. K. 
Published: February 2015

Abstract
The stability of Kelvin-Helmholtz flow at the second harmonic resonance between two marginally unstable modes is investigated in the presence of a tangential electric field. We obtain coupled amplitude equations which are examined for the stability characteristics. Numerical integration of the equations reveals that at a certain determinate time, the amplitudes of both the fundamental mode and the second harmonic mode start increasing rapidly, resulting in what is termed as "Explosive Instability". It is demonstrated that for a fluid of given density and dielectric constant, the electric field plays an important role, and the explosive instability sets in much earlier as the electric field increases.
The 2ν5 Overtone Band of Cyanoacetylene by High Resolution FTIR Spectroscopy
Authors: Yamada K. M.T. , Moravec A. , Niedenhoff M. , Bürger H. , Winnewisser G. 
Published: February 2015

Abstract
The 2ν5 overtone band of cyanoacetylene, HCCCN, has been measured with a high resolution FTIR spectrometer. The analysis of the accidental resonances results in very accurate parameters for the observed ν5 = 2 state as well as for the hidden perturber state (ν4 = 1, ν7 = 2); the vibrational energy and the rotational constant have been determined to be 1312.991921(23) cm-1 and 4552.38440(23) MHz for the ν5 = 2 state, and 1310.0627(6) cm-1 and 4572.463(4) MHz for the (ν4 = 1, ν7 = 2) state. The associated hot bands from the ν7 = 1, ν6 = 1, and ν5 = 1 state have also been analyzed.
An ab initio Study of the Molecular Electric-field Gradients of the Chlorsilanes
Authors: Suter H. U. , Maric D. M. , Meier P. F. 
Published: February 2015

Abstract
The electric field gradient (EFG) of chlorine in the chlorine containing silanes (SiCl4 , SiCl3H, SiCl2H2 , and SiClH3) was determined by means of ab initio methods and compared to recent experiments from which nuclear quadrupole moments are extracted. A careful estimation of the AO basis sets and the effect of the electron correlation is undertaken. The results showed the importance of the use of extended basis sets in the calculation of EFGs in second row atoms. Good agreement with deviations less than 5% from the experiments was found. The effect of the electron correlation was found to be small.
Microwave and Millimeterwave Spectrum of 1,1-Difluoroethylene and the Vibrational Mode ν10 from FT-IR Spectroscopy
Authors: Zerbe-Foese H. , Guarnieri A. , Stiefvater O. L. 
Published: February 2015

Abstract
Pure rotational spectra of 1,1-Difluoroethylene (1,1-DFE) in the vibrational ground state (GS) and in excited vibrational states (EVSs) have been investigated by double resonance modulation (DRM) microwave spectroscopy in the range from 12 GHz to 40 GHz, and by millimeterwave spectroscopy in the range from 90 to 260 GHz.
In addition to the GS spectrum, rotational transitions have been observed for the EVSs ν10 = 1, and 2, ν12 = 1, ν6 = 1, ν11 = 1, ν4 = 1, and ν9 = 1. Along with other IR bands up to 1400cm-1 , the fundamental vibrational band ν10 = 1 ← 0 has been observed by FT-IR spectroscopy and has been analysed to yield ν10
0 = 436.8851 cm-1.
Rotational constants and quartic distortion constants were deduced for all observed states. In addition, sextic distortion constants were obtained for the GS and for the EVSs ν10 = 1, 2, ν6 = 1, and ν12 = 1 by computer fits of combined microwave and millimeterwave data to Watson's A-reduced Hamiltonian in Ir representation. The S-reduced Hamiltonian in IIIr representation may be considered more appropriate for the calculation or the fitting of the transitions because 1,1-DFE is a near oblate asymmetric top. Thus, for comparison, results are given for both the A- and the S-reduction.
Determination of the Partial Structure Factors of Amorphous CuZr by Anomalous X-Ray Scattering and Reverse Monte Carlo
Authors: Bionducci M. , Buffa F. , Licheri G. , Navarra G. , Bouchet-Fabre B. , Tonnerre J. M. 
Published: February 2015

Abstract
Anomalous X-ray Scattering experiments have been performed to study the local order in an amorphous CuZr sample prepared by mechanical alloying. The three partial structure factors were extracted both using a regularization algorithm to solve an ill-conditioned system of linear equations and applying the reverse Monte Carlo technique to the experimental data. Then the short range atomic distributions of similar samples prepared by different methods and investigated by different techniques are compared.
The Role of Conjugative Interaction in Stable Carbenes of the 1,2,4-Triazol-5-ylidene Type and their Energy of Dimerization. An Ab Initio Study
Authors: Raabe Gerhard , Breuer Klaus , Enders Dieter , Teles J. Henrique 
Published: February 2015

Abstract
The role of conjugative interaction in stable carbenes of the 1,2,4-triazol-5-ylidene type was studied at different levels of ab initio theory employing model compounds. In the case of parent 4,5-dihydro-1 H-1,2,4-triazol-5-ylidene this type of interaction was found to be of similar importance as in 1,2,4-triazole and pyridine.
Five stationary points were located on the hypersurface of the dimer (C2N3H3)2 . ΔE for all considered dimerization reactions was found to be negative, and the change of energy associated with the formation of the most stable isomer is about -9.5 kcal/mol. In spite of a high value for the singlet-triplet gap of about 90 kcal/mol for the carbene, the heavy atom skeleton of the most stable dimer is close to planarity. This finding is in perfect accordance with the predictions of other authors regarding the geometry of dimers from singlet carbenes stabilized by π-conjugation.
Reaction of Trimethyl-and Dimethyl-Silyl Radicals with Pentamethyldisilane
Authors: Kerst C. , Potzinger P. , Wagner H. Gg. 
Published: February 2015

Abstract
The rate constant for the H atom abstraction of trimethylsilyl radicals from pentamethyldisilane (k(4)) was measured relative to the trimethylsilyl combination reaction k(3). A value for

=(8.53 ± 0.08) · 10-11cm3/2s–1/2 was obtained. For the dimethylsilyl radical, a smaller value for the corresponding rate constant ratio (5.9 ± 0.2) · 10-11 cm3/2 s–1/2 was measured, and this was attributed to a disproportionation reaction between the dimethylsilyl and the pentamethyldisilyl radical leading to dimethylsilylene.
Charge-Transfer Complexes Between Iodine and Substituted Thioureas: Determination of Thermodynamic and Spectroscopic Properties
Authors: Fooken Cornelia , Baumann Wolfram 
Published: February 2015

Abstract
15 iodine complexes with substituted thioureas were investigated in dichloromethane solution by UV-visible spectroscopy, and their equilibrium constants, reaction enthalpies and molar absorption coefficients were determined. The influence of the substituents on the properties of the charge-trans-fer complexes is examined. A critical discussion of previously published data is given, where comparable data are available.
EPR Investigation of VO2+ Ion in [C(NH2)3]3 AIF 6 Single Crystals
Authors: Kasturi T. Lakshmi , Jayaram Geetha , Krishnan V. G. 
Published: February 2015

Abstract
X-band EPR spectra have been recorded at room temperature for VO2+ impurity in single crystals of tris-Guanadiniumhexafluoroaluminate, [C(NH2)3]3 AIF6. 19F super hyperfine structure has been observed on the 51V hyperfine lines. VO2+ replaces Al3+ to form an effective VOF5 complex. There are three possible V-O bond orientations in the AIF6 octahedron but with differing occupancy factors. Bonding parameters have been evaluated.
Enumeration of Chemical Isomers of Polycyclic Conjugated Hydrocarbons with Six-Membered and Five-Membered Rings
Authors: Brunvoll J. , Cyvin B. N. , Cyvin S. J. , Brinkmann G. , Bornhöft J. 
Published: February 2015

Abstract
Polygonal systems P consist of exclusively hexagons and pentagons. They correspond (as chemical graphs) to a certain class of polycyclic conjugated hydrocarbons. This class includes protofullerenes. General formulations for the maximum numbers of internal vertices for P systems with p<6 are derived; here p is the number of pentagons. The CnHs chemical formulas of P systems are studied with special emphasis on the semibuckminsterfullerene (C30H12) , circum-semibuckminsterfullerene (C58H16) and corannulene (C20H10) isomers. Numbers of all CnHs isomers for P systems with r< 6 are computed; here r is the total number of polygons.
EPR Spectroscopy of Some Mn2+ Doped Langbeinites with Regard to Low Temperature Phases
Authors: Böttjer T. , Stockhausen M. 
Published: February 2015

Abstract
Electron paramagnetic resonance (EPR) spectra of Mn2+ centers in 11 langbeinites, A2
+B2
2+ (SO4)3
2-, with A+ = NH4
+, K+, Rb+ or Tl+ and B2+ = Mg2+, Ca2+, Zn2+ or Cd2+, are measured over relatively large temperature ranges chosen to cover phase transitions, if any. For 7 langbeinites which do not contain Mg2+, phase transitions are observed, but no more than one low temperature phase is distinguishable by EPR. Except for the K-Zn langbeinite, only one defect center is noticeable in that phase. The low temperature EPR parameters are reported, and their temperature dependence is discussed with respect to correlations between structure and phase transition characteristics and to the trigger mechanism.
Methane as Carrier Gas for Molecular Beam Microwave Spectroscopy to Observe Transitions of Higher Rotational Energy Levels
Authors: Lorenzo F. , Grabow J.-U. , Dreizler H. 
Published: February 2015

Abstract
We report on an observation in molecular beam rotational spectroscopy: using Methane rather than rare gases as carrier extends the range of observable transitions towards levels of higher rotational energy.
The 33S Nuclear Quadrupole Coupling in the Rotational Spectrum of anti-2,3-Dimethylthiirane
Authors: Grabow Jens-Uwe , Dreizler Helmut 
Published: February 2015

Abstract
The rotational spectrum of 33S anti-2,3-dimethylthiirane with its 33S nuclear quadrupole coupling hyperfine structure in the range 7.6 to to 21.5 GHz and its analysis is reported. The rotational constants are A = 5331.1401(5), B = 3506.3963(10), and C = 2356.9273(2) MHz. The 33S quadrupole coupling constants are χaa = 8.3871(93), χbb = -32.3291(174), and χcc = 23.9420(174) MHz.
EPR Studies of Cr3+ and Fe3+ in Host Crystals with Langbeinite Structure
Authors: Kastner J. , Mosel B. D. , Müller-Warmuth W. 
Published: February 2015

Abstract
Electron paramagnetic resonance (EPR) spectra of trivalent chromium and iron ions have been investigated in host crystals of double sulfates with langbeinite structure, A2B2(SO4)3 , with A = NH4
+, Rb+, Tl+ and B = Cd2+, Mg2+. In most cases, single crystals could be grown, and the spin Hamiltonian parameters have been determined from the rotational diagrams. Powder spectra were analyzed and simulated as well. Three centres of axial symmetry with different zero field splittings have been observed for Cr3+, and two for Fe3+. The trivalent impurity ions have been shown to occupy divalent lattice sites substitutionally, but the environments are different depending on the structure and the mechanism of charge compensation. A qualitative description of the incorporation of dopants has been possible on this basis, taking into account the local relaxation and the ligand field stabilization effects. Temperature dependent single crystal and powder measurements have provided information on the zero field splitting and phase transitions.
Dissociation of Slow Polyatomic Molecules by Grazing Scattering at Surfaces
Authors: Schmidt L. , Popova A.M. , Komarov V.V. , Jungclas H. 
Published: February 2015

Abstract
We consider polyatomic molecules containing peripheral chains of valence groups, which slide along crystallic surfaces at grazing incidence. The periodically located Coulomb centres of the crystallic surfaces interact with the moving valence group dipoles like a time-dependent oscillation potential. This interaction can lead to multiple resonant vibrational excitations of the peripheral valence group dipoles. Accumulation of such collective excitations in the valence group chains (excimols) eventually can lead to the cleavage of particular bonds (trap bonds) inside the molecule. A model for this complex process is presented including a parameterised formula for the dissociation probability of polyatomic molecules scattered by a surface at grazing incidence. The model is supported by the experimental observation of dissociation energy thresholds.
Photoluminescence Properties of trans–4,4'–Diamino–stilbene in Poly(vinyl alcohol) Films
Authors: Kawski A. , Kubicki A. , Kukliński B. , Nowosielski T. 
Published: February 2015

Abstract
Experimental studies have shown that the nonpolar molecule 4,4'-diamino-stilbene (DAS) in poly(vinyl alcohol) film (PVA) at 296 K, apart from fluorescence displays phosphorescence whose intensity differs only slightly from that observed at 84 K. The overlapping of fluorescence and phosphorescence bands is the reason of the unusual behaviour of the emission anisotropy in the longwave absorption and photoluminescence bands. A distinct effect of direct irradiation on the intensity of these bands was observed.
Pattern Formation in Force-free Magnetic Fields and Beltrami Flows
Authors: Qing-Zeng Feng 
Published: February 2015

Abstract
Force-free magnetic fields and Beltrami flows, which are selenoidal vector fields and satisfy the condition that the field vector is everywhere parallel to its curl, have complex topological structures and usually show chaotic behavior. The lines of force are determined by the equations of a 3-D (dimensional) dynamical system. In the integrable case, all lines of force lie on some families of tori. If the integrable solution undergoes a small perturbation, most of the original tori still exist but undergo a slight distortion (KAM tori). Near the original heteroclinic cycles emerges a chaotic layer. By superposition of the basic solutions of force-free magnetic fields one can get very complicated pictures: a single line of force could be space filling within some subspace of a 3-D region, which has a fractional dimension and a positive Lyapunov exponent, i.e. one gets a chaotic line of force or a fractal. At the same time there are still ordered regions in the chaotic surroundings. Tubes of force which are tangled or self-knotted embed in the chaotic sea. The KAM tori can also be disrupted through resonances, leading to increased chaotic regions. Thus, the effect of nonlinear dynamics plays an important role in the pattern formation of force-free magnetic fields and Beltrami flows.
The Critical Amplitude for Bifurcation Points of the Logistic Map
Authors: Tsuchiya Takashi 
Published: February 2015

Abstract
The phenomenon called critical slowing down is studied for some analytically tractable bifurcation points of the logistic map. The critical amplitude and the critical amplitude ratio are introduced to describe the critical behaviors more precisely when the critical exponents are identically unity for two critical behaviors which are to be compared. Since Hao predicted unity of the critical exponent for 1-d maps assuming exponential damping of the distance from the attractor, the assumption is checked. The result is that the shrinkage of the valid region of the assumption occurs as the adjustable parameter approaches one of the bifurcation points.
The ‘‘Triptych” Function -Determining the Basins of Attraction of One-Dimensional Maps
Authors: Moreira I. C. 
Published: February 2015

Abstract
We show that a modification of the path length method, introduced by R. Richter et al. [Z. Naturforsch. 49 a, 871 (1994)], gives us a method for finding basins of attraction of one-dimensional maps with multiple attractors.
A Diffraction Study of Amorphous Si0.40C 0.24N0.36
Authors: Uhlig H. , Frieß M. , Dürr J. , Bellissent R. , Lamparter H.-P. , Aldinger F. , Steeb S. 
Published: February 2015

Abstract
In the present work, amorphous Si0.40C0.24N0.36 samples were investigated. X-ray and neutron diffraction experiments were performed, in order to evaluate the structure factors by the method of contrast variation. The structure can be described as crosslinked Si-N-C matrices. Within these matrices SiN4 tetrahedra are predominant. Direct Si-Si contact does not occur. We report on the short range order and the nature of chemical bonding.
Study of Orientational Order of Liquid Crystal 8 OCB Doped with Perylene-like Dyes by Means of Polarized Optical Spectroscopy
Authors: Bauman Danuta , Wolarz Eryk 
Published: February 2015

Abstract
Measurements of the polarized absorption and fluorescence spectra for perylene-like dyes dis-solved in a liquid crystal 8 OCB have been used to study the long-range orientational order in the smectic A and nematic phases. The temperature dependence of the order parameters <P2> and <P4> has been investigated and the orientational distribution function has been determined. On the basis of the experimental order parameter values some information about the orientation of molecules in guest-host mixtures has been obtained.
Dielectric Investigations in Smectic B-Phases
Authors: Heinemann S. , Kresse H. , Urban S. , Dabrowski R. 
Published: February 2015

Abstract
Several liquid crystalline substances exhibiting SB -phases have been investigated by dielectric and calorimetric measurements. Special attention is taken to the low frequency relaxation process at the phase transition nematic-SB . From the large change of relaxation frequencies, crystallinity of the SB -phases has been concluded. Nevertheless, motion is still present and not frozen.