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1982[X]
21Author    D. Hübner, M. Stolze, D. H. SutterRequires cookie*
 Title      
 Abstract    The lower part of Table 4 of our paper [1] con-tained several printing errors. In view of the rising interest in experimental values for the second moments of the molecular charge distribu-tion the corrected Table is given below. The ab-breviations have the following meanings: Zn = atomic number of w-th nucleus, an, bn, cn = coordinates of the w-th nucleus, 
  Reference    Z. Naturforsch. 37a, 95—96 (1982); received November 16 1981 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0095_n.pdf 
 Identifier    ZNA-1982-37a-0095_n 
 Volume    37 
22Author    BhimsenK. ShivamoggiRequires cookie*
 Title    Decay Instability of an Electromagnetic Wave Incident on a Weakly-Inhomogeneous Magnetised Plasma  
 Abstract    This paper considers the parametric decay of an electromagnetic wave incident on a weakly-inhomogeneous magnetised plasma into a Langmuir wave and an ion-acoustic wave. The Vlasov model is used in order to calculate the low-frequency electron-density perturbation produced by the beating of the side-band modes with the pump wave. The results show that the threshold value of the pump wave to undergo a decay instability drops in the presence of an inhomogeneity in the plasma. 
  Reference    Z. Naturforsch. 37a, 97 (1982); received September 1981 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0097.pdf 
 Identifier    ZNA-1982-37a-0097 
 Volume    37 
23Author    G. Klages, E. WieczorekRequires cookie*
 Title    Molekülinterne Dipolorientierung und dielektrische Absorption in verdünnter Lösung bei Mikro-und Submillimeter-Wellen. I. Primäre Amine Intramolecular Dipole Reorientation and Dielectric Loss of Microwaves and, Submillimetrewaves in Diluted Solution I. Primary Amines  
 Abstract    The dielectric loss of very diluted solutions of four aromatic and three aliphatic amines in three non polar aliphatic solvents at 20 °C has been measured. The wave numbers cover 0.1 to 200 cm -1 . It is shown, how to analyse the microwave spectra of the loss factor e" in terms of three absorption areas, two of Debye relaxation type and the high frequency one of Lorentz resonance type. To limit the latter at its high frequency side, the extinction coefficient a has been used to determine and separate the lowest molecular resonances. From the analysis, dispersion steps and the com-ponents of the dipole moment due to the three absorption regions are calculated. Comparison with the so called optical dispersion step insures within the limits of experimental error that the absorption due to orientation of the permanent dipole moment is covered by the measured band. The long wave region belongs to the rotation of the molecules, the two others to intramolecular reorientation. In aromatic amines not all molecules of the sample are able to i nvert their NH2 group, but slower orientation by hindered inversion happens. On the other hand, in aliphatic amines the group is rotating and the high frequency region may be due to Foley absorption. 
  Reference    Z. Naturforsch. 37a, 102—112 (1982); eingegangen am 5. Januar 1982 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0102.pdf 
 Identifier    ZNA-1982-37a-0102 
 Volume    37 
24Author    G. Klages, E. WieczorekRequires cookie*
 Title    Molekülinterne Dipolorientierung und dielektrische Absorption in verdünnter Lösung bei Mikro-und Submillimeterwellen. IL Sekundäre und tertiäre Amine  
 Abstract    Supplementary to a preceding investigation on primary amines, the dielectric loss increments of three aromatic dimethylamino compounds, diphenylamine, N-methyldiphenylamine and triphenylamine, and of dicyclohexylamine have been measured in very diluted solutions at 20 °C. The loss data resulting from 0.1 up to 250 cm -1 are now covering the complete absorption region due to reorientation of the permanent molecular dipole, especially that part based on inversion. To resolve this part, the absorption curves are analysed in terms of three areas using the same method as done for primary amines. By this the dipole components assigned to the special re-orientation processes may be discerned and discussed. So the dipole component of the dimethyl-amino group which reorientates by intramolecular motion is smaller than that of the amino group. The occurrence of an inversion process is demonstrated, but the molecular dipole component governing it also may reorient more slowly as the result of a hindered inversion. The additional reorientation of a mesomeric moment by twisting of the phenyl groups is suggested in triphenyl-amine and in the diphenyl compounds. The aliphatic dicyclohexylamine only shows a Poley ab-sorption area, increased perhaps by intramolecular libration. 
  Reference    Z. Naturforsch. 37a, 113—124 (1982); eingegangen am 20. Januar 1982 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0113.pdf 
 Identifier    ZNA-1982-37a-0113 
 Volume    37 
25Author    Tae-Kyu Ha, M. T. Nguyen, L. VanquickenborneRequires cookie*
 Title    Ab Initio Calculations of the Molecular Structures and the Electronic Properties of Sulfur-containing Compounds: III. Thioacrolein (CH 2 = CH—CH=S) and Thioglyoxal (S = CH—CH = S)  
 Abstract    Results of ab initio SCF calculations on thioacrolein (CH2=CH—CH=S) and thioglyoxal (S=CH—CH=S) are reported. The geometries are optimized by the analytical gradient method using the double zeta (DZ) basis set. The trans conformers of these molecules are calculated to be more stable than the eis conformer by 2.06 and 4.31 kcal/mol, respectively. 
  Reference    Z. Naturforsch. 37a, 125—128 (1982); received December 12 1981 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0125.pdf 
 Identifier    ZNA-1982-37a-0125 
 Volume    37 
26Author    JoseL. Alonso, J. C. Lopez, F. MataRequires cookie*
 Title    Microwave Spectrum of y-Thiobutyrolactone  
 Abstract    The microwave spectrum of y-thiobutyrolactone has been observed and measured in the vibra-tional ground state and in several excited states of the ring-bending and ring-twisting modes. From the value of the /ic component of the dipole moment and inertial-defect considerations the ring skeleton was shown to be non-planar. The average intensity ratio for the rotational transi-tions between the ground and excited vibrational states indicates that the first excited state of the ring-bending and ring-twisting modes are ~ 120 cnr 1 and ~ 250 cm -1 above the ground state respectively. These two out-of-plane ring vibrations are essentially independent and the ring-bending vibration is governed by a nearly harmonic potential energy function. The components of the dipole moment were determined by the Stark effect to be /ia = 3.770 ± 0.001 D, = 1.818 ±0.044 D and /ic = 0.832 ±0.018 D, leading to /«total = 4.268 ± 0.023 D. The rigidity of the y-thiobutyrolactone ring is discussed in relation to those of related molecules. 
  Reference    Z. Naturforsch. 37a, 129—133 (1982); received November 7 1981 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0129.pdf 
 Identifier    ZNA-1982-37a-0129 
 Volume    37 
27Author    ÄrpadI. Kiss, Istvan HargittaiRequires cookie*
 Title    Theoretical Study on the Molecular Geometries of Substituted Fluoroforms  
 Abstract    The F ... F non-bonded distances are strikingly constant in a large series of trifluoromethyl derivatives. Semiempirical NDD0 calculations have been performed for five representative molecules. From the energy partitioning it appears that the bonding interactions (resonance energy terms) are dominating in determining the molecular geometry. The constancy of the non-bonded distances may occur as the changes in the bond lengths and bond angles are compensated. A good description of the total energy, however, necessitates the inclusion of the two-center electrostatic terms of all atom pairs. 
  Reference    Z. Naturforsch. 37a, 134—138 (1982); received December 15 1981 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0134.pdf 
 Identifier    ZNA-1982-37a-0134 
 Volume    37 
28Author    Kurt Paulsen, Dieter RehderRequires cookie*
 Title    Nuclear Quadrupole Perturbations in 51 V NMR Spectra of Oxovanadium(+V) Complexes  
 Abstract    Nuclear electric quadrupole coupling constants e 2 qQ/h have been obtained by evaluation of quadrupole perturbations in 51 V NMR spectra of various vanadyl esters and esterchlorides of the general formula VOCl3_"(OR)n («, = 0-3; = Me, Pr ra , Pr*, Bu» and Bu«). e 2 qQlh values have been calculated from (i) 2nd. order quadrupole splittings of the 51 V NMR signals in pseudo-polycrastalline samples, (ii) 1st. order quadrupole splittings in nematic liquid crystals and (iii) line widths A v\ti of the 51 V and 35 C1 NMR signals in the liquid isotropic state and e 2 qQ/h(35 CI) obtained by pure NQR measurements. The influences of the asymmetry parameter r) and the orientation of the crystallites in powder spectra are considered, and temperature and concen-tration effects upon Zbi/2 and 51 V shielding (isotropic phases) and the ordering factor (meso-phases) are discussed. 
  Reference    Z. Naturforsch. 37a, 139—149 (1982); received November 7 1981 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0139.pdf 
 Identifier    ZNA-1982-37a-0139 
 Volume    37 
29Author    C. BojarskiRequires cookie*
 Title    Remarks on Concentration Quenching in Chlorophyll  
 Abstract    A quantitative analysis of fluorescence self-quenching of chlorophylls a and b in ether as well as chlorophyll a in lipid vesicles and liposomes has been carried out. It is demonstrated that con-centration changes of the fluorescence quantum yield can be correctly described by a Förster-type excitation energy transfer process between chlorophyll molecules in the monomeric form if part of the transfers leads to energy degradation. 
  Reference    Z. Naturforsch. 37a, 150—153 (1982); received December 7 1981 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0150.pdf 
 Identifier    ZNA-1982-37a-0150 
 Volume    37 
30Author    G. PiccalugaRequires cookie*
 Title    X-ray Diffraction Study of the Coordination of Fe(III) in a Highly Hydrolyzed Solution of Iron(III) Chloride  
 Abstract    A highly hydrolyzed solution of iron(III) chloride is investigated by X-ray diffraction. The occurrence of six 0 atoms in the first coordination shell of iron(III) is demonstrated. The struc-tural similarity of hydrolyzed solutions of Fe(III) chloride and nitrate is pointed out. 
  Reference    Z. Naturforsch. 37a, 154—157 (1982); received October 10 1081 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0154.pdf 
 Identifier    ZNA-1982-37a-0154 
 Volume    37 
31Author    Isao Okada, Tetsuo Ayano, Kazutaka KawamuraRequires cookie*
 Title    The Chemla Effect in the Internal Mobilities of (Li-NH 4 )N0 3 Melts  
 Abstract    Internal mobility ratios in melts of the system (Li-NH4)N03 were measured with the Klemm method. Densities and electric conductivities of this system were also measured. From these data the internal mobilities &Li and 6NH4 were calculated. On account of the inevitable thermal de-composition of NH4NO3 the range of temperatures and concentrations was limited. In these the mobility of NH4 4 " is considerably greater than that of Li+. In contrast to other binary nitrate systems, the isotherms of the internal mobility of the larger cation distinctly decrease with a decrease of its concentration, in which the fact that NH4NO3, whose cation is moderately light though large in size, melts at relatively low temperature is reflected. The isotherms of &Li and 6NH4 and the temperature dependence are discussed on the basis of the autor's interpretation so far presented. 
  Reference    Z. Naturforsch. 37a, 158—164 (1982); received December 21 1981 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0158.pdf 
 Identifier    ZNA-1982-37a-0158 
 Volume    37 
32Author    M. Schadt, P. R. GerberRequires cookie*
 Title    Class Specific Physical Properties of Liquid Crystals and Correlations with Molecular Structure and Static Electrooptical Performance in Twist Cells  
 Abstract    For the 65th aniversary of Professor Walter Boguth We made measurements of the temperature dependence of the static dielectric constants, the optical anisotropy and the three elastic constants of binary mixtures belonging to twelve struc-turally and physically markedly different liquid crystal classes. The class-specific material properties were quantitatively correlated with molecular structural elements. The changes of material properties occurring when different LC-classes are combined were investigated. Analytical approximations are presented which are shown to reproduce the static transmission characteristics of twisted nematic cells and their dependence on material constants and temperature with an accuracy comparable to exact numerical calculations. Strong smectic pretransitional effects are shown to influence not only £22 and £33 but also k\\, thus suggesting that not only twist and bend but also splay deformations may be prohibitive in smectics. We show that the elastic ratio &33/&11 of different liquid crystal classes increases with increasing dielectric anisotropy thus leading to a decrease of the slope of transmission characteristics of twist cells. Furthermore, it is shown that &33/&11 decreases for molecules comprising heterocyclic rings whereas hydrogenation of an aromatic ring causes &33/&11 to increase. 
  Reference    Z. Naturforsch. 37a, 165—178 (1982); received February 3 1982 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0165.pdf 
 Identifier    ZNA-1982-37a-0165 
 Volume    37 
33Author    PaulR. Gerber, M. SchadtRequires cookie*
 Title    Viscous Properties and Dynamic Electrooptical Performance in Twisted Nematic Displays of Several Liquid Crystal Classes  
 Abstract    For the 65th aniversary of Professor Walter Boguth The temperature dependence of the rotational viscosities of several physically markedly dif-ferent binary mixtures belonging to ten different liquid crystal classes is measured. An attempt is made to correlate the results with class-specific structural properties such as hydrogenated rings, molecular polarity and structure of flexible side-chains. It is show that the measured small-scale dynamic properties of twist cells compare well with approximative theoretical calculations and experimentially determined class-specific material parameters. For the switching times cor-responding to large-scale twist deformations heuristic approximations lead to satisfactory results. 
  Reference    Z. Naturforsch. 37a, 179—185 (1982); received February 3 1982 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0179.pdf 
 Identifier    ZNA-1982-37a-0179 
 Volume    37 
34Author    Peter Kroneck, Jürgen Kodweiß, Otto Lutz, Alfons Nolle, Daniela ZepfRequires cookie*
 Title    63 Cu NMR Studies of Copper (I) Complexes in Solution: Influence of Anion, Solvent and Temperature on the Linewidth and Chemical Shift of the Copper Resonance  
 Abstract    The behaviour of the 63 Cu nuclear magnetic resonance signals in tetrahedrally coordinated copper(I) complexes has been investigated as a function of temperature, solvent and anion. Frcm the strong dependence of the linewidth and the chemical shift on these parameters, ex-change processes with complexes of lower symmetry are concluded. 
  Reference    Z. Naturforsch. 37a, 186—190 (1982); received January 27 1982 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0186.pdf 
 Identifier    ZNA-1982-37a-0186 
 Volume    37 
35Author    H.G K Sundar, R. Parthasarathy, K. J. RaoRequires cookie*
 Title    Infrared Band-Shape Studies of Sulphate Glasses  
 Abstract    IR band-shape analysis has been carried out on the 620 cm -1 deformation band of the sulphate ion in several Na2S04-K2S04-ZnSC>4 glasses. Variations of correlation times and second moments suggest that reorientational motions of sulphate ions begin to evolve prior to the glass-transition temperature. The correlation times may support a cluster model for the glass-transition. 
  Reference    Z. Naturforsch. 37a, 191—195 (1982); received December 15 1981 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0191.pdf 
 Identifier    ZNA-1982-37a-0191 
 Volume    37 
36Author    H. TassoRequires cookie*
 Title    Explicit Liapunov Functions for a Class of Dissipative Systems with Circulatory Forces  
 Abstract    A class of dissipative systems with circulatory forces is given for which a necessary and sufficient condition for stability can be expressed as an explicit Liapunov function equivalent to the Hermitian form of a Hermitian matrix. For a discretized continuous system this matrix has a band structure. 
  Reference    Z. Naturforsch. 37a, 196 (1982); received January 28 1982 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0196_n.pdf 
 Identifier    ZNA-1982-37a-0196_n 
 Volume    37 
37Author    R. K. Bauer, R. TwardowskiRequires cookie*
 Title    Measurements of the Fluorescence Decay Time in Mixed Solutions Using Pulse Fluorometery  
 Abstract    The mean fluorescence decay time for rhodamine 6G (donor) in the presence of malachite green (acceptor) has been investigated using a pulse fluorometer. The experi-mental results have been compared with theoretical ones obtained earlier [1]. One of the commonly investigated luminescence quantities is the mean fluorescence decay time (MFDT) T: r = jt0(t)dtl S&{t)dt, o o (1) 
  Reference    Z. Naturforsch. 37a, 197—198 (1982); received October 19 1981 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0197_n.pdf 
 Identifier    ZNA-1982-37a-0197_n 
 Volume    37 
38Author    J. Demaison, H. DreizlerRequires cookie*
 Title    Quadrupole Coupling in Butyronitrile An Application of Microwave Fourier Transform Spectroscopy  
 Abstract    The microwave spectrum of butyronitrile, CH3CH2CH2CN, was already investigated by Hirota [1]. But he could not observe the quadrupole hyperfine structure due to the nitrogen nucleus 
  Reference    Z. Naturforsch. 37a, 199—200 (1982); received February 2 1982 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0199_n.pdf 
 Identifier    ZNA-1982-37a-0199_n 
 Volume    37 
39Author    M. SorgRequires cookie*
 Title    Geometrization of the Lienard-Wiechert Field  
 Abstract    A geometric description of the Lienard-Wiechert field of a single point charge is given. The dual of the Lienard-Wiechert field can be considered as the curvature in a bundle of 2-planes distributed smoothly over space-time. This geometric construction also accounts for the Teitel-boim splitting of the total field into bound and radiative parts: The radiation field can be identified with the curvature in the normal bundle. Various questions concerning potentials and the in-tegrability of the distributions involved are discussed. Whereas the intrinsic symmetry group for the field is that of the 2-plane bundle, namely SO (2), the normal bundle approach leads to the group SO (1,1) as the internal symmetry group for the radiation field. 
  Reference    Z. Naturforsch. 37a, 201—207 (1982); received August 21 1981 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0201.pdf 
 Identifier    ZNA-1982-37a-0201 
 Volume    37 
40Author    P. Mulser, H. Takabe, K. MimaRequires cookie*
 Title    Resonant Excitation of High Amplitude Oscillations and Hydrodynamic Wave Breaking in a Streaming Cold Plasma Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V.  
 Abstract    The excitation of large amplitude electron oscillations in a streaming cold plasma and the minimum threshold of wave breaking in the resonant region are investigated analytically as a function of flow velocity. The problem is reduced to the solution of a driven harmonic oscillator with time varying eigenfrequency cop(<) in a self-consistent, stationary ion density profile. An analytical solution is presented and applied to the correct wave breaking criterion in a streaming plasma. Wave breaking sets in when the driver amplitude obeys the inequality me(ovc v \ -f ir/eii 2 j" drj, — oo which shows that the threshold is proportional to the driver frequency co and to the flow velocity at the resonance point, vc; however, it is independent of the density scale length. Resonance ends at rj = jr/2. The denominator assumes there the value 2.759. rj is a dimensionless time which measures the transit time of a volume element through resonance. 
  Reference    Z. Naturforsch. 37a, 208—218 (1982); recived February 20 1982 
  Published    1982 
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 TEI-XML for    default:Reihe_A/37/ZNA-1982-37a-0208.pdf 
 Identifier    ZNA-1982-37a-0208 
 Volume    37 
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