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1988 (183)
81Author    SalimM. KhalilRequires cookie*
 Title      
 Abstract    MINDO-Forces calculations have been performed, after complete optimization of geometry, on fulvene molecule, fulvene and X-fulvene radical cations, where X is OH, NH2, CH3, N 02, CN and F. A twisted structure with angle 5° was found for fulvene radical cation. The substituents OH, NH2, CH3, CN and F are stabilizing. N02 is slightly stabilizing. Geometrical parameters, heats of formation, dipole moments and electron densities are reported. A T h e o r e tic a l S tu d y o f F u lv e n e R a d ic a l C a tio n s 
  Reference    Z. Naturforsch. 43a, 485—493 (1988); received February 1 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0485 
 Volume    43 
82Author    Lothar Ohse, Wolfgang BrocknerRequires cookie*
 Title      
 Abstract    Molecular Vibration Analysis of the Hexathiometadiphosphatanion P2Sl~~ A normal coordinate analysis for the Hexathiometadiphosphate anion P2Sj;~ was performed, based on a simple initial force field. The force field was refined by adjusting the symmetry force constants to approximate the observed frequencies. The final force field, potential energy distribu­ tion (PED) and mean amplitudes of vibration are also given. Based on the normal coordinate analysis a new assignment of the P2Sg~ frequencies is proposed. S c h w in g u n g s b e re c h n u n g e n d e s H e x a th io m e ta d ip h o s p h a ta n io n s P 2Sö 
  Reference    Z. Naturforsch. 43a, 494—496 (1988); eingegangen am 22. März 1988 
  Published    1988 
  Keywords    P2Sg~, Vibration Spectrum, Normal Coordinate Analysis 
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 Identifier    ZNA-1988-43a-0494 
 Volume    43 
83Author    B. Boddenberg, R. GroßeRequires cookie*
 Title      
 Abstract    2H NMR solid state powder patterns were measured at one monolayer coverage of benzene on the non graphitized carbon black Spheron, and of toluene, p-xylene, mesitylene, and mellitene (hexamethylbenzene) on the graphitized carbon black Graphon. Benzene on Spheron, in contrast to Graphon, exhibits a typical Pake type powder pattern shape demonstrating the minor influence of paramagnetic centers on the pattern shapes as well as confirming the formerly introduced shielding anisotropy interaction in the case of graphite. From the highly asymmetric appearance of the 2H powder patterns for the adsorbed methyl-aromatics on Graphon the flat orientation of these molecules on graphite as well as details of the rotational molecular motions are deduced. 2H N M R P a t te r n s o f M e th y la r o m a tic s A d s o rb e d o n G r a p h ite 
  Reference    Z. Naturforsch. 43a, 497—504 (1988); received March 11 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0497 
 Volume    43 
84Author    E. Matsubara, Y. Waseda, A. P. Tsai, A. Inoue, T. MasumotoRequires cookie*
 Title    On the Structural Evolution of the Amorphous Al75Cu15V10 Alloy to the Icosahedral Phase  
 Abstract    The transformations occurring on annealing an as-spun amorphous Al75Cu15V10 alloy are studied by X-ray diffrac­ tion and transmission electron microscopy (TEM). A contin­ uous growth of icosahedral clusters, which are present al­ ready in the as-spun sample, is revealed. The size of the clusters estimated from the diffuse X-ray peak widths is con­ sistent with the size of the modulation observed in the bright field TEM images. 
  Reference    Z. Naturforsch. 43a, 505—506 (1988); received February 17 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0505_n 
 Volume    43 
85Author    H. Neger, JägerRequires cookie*
 Title     
 Abstract    Relative transition probabilities of 7 Cull lines in the visible spectral region have been measured by side-on ob­ servation of a plasma jet emerging out of a capillary as well as by using an axial discharge-type of an exploding copper wire. The results are compared with those of two other ex­ periments. 
  Reference    Z. Naturforsch. 43a, 507—508 (1988); received March 19 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0507_n 
 Volume    43 
86Author    Wilfred KrauseRequires cookie*
 Title      
 Abstract    The original Eötvös data, which had resulted from a measurement series completed in 1908, and which recently found renewed interest, were not formally published until 1922. Now a resuming letter, written by Eötvös eighty years ago, has been re-discovered. The letter throwing some additio­ nal light on his experiments is translated and briefly commented. L e tte r fro m E ö tv ö s 
  Reference    Z. Naturforsch. 43a, 509—510 (1988); received March 8 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0509 
 Volume    43 
87Author    Takao Oi, Makoto Aikawa, Hidetake Kakihana, Takanobu IshidaRequires cookie*
 Title      
 Abstract    e r o -P o in t E n e r g y S h ifts in H y d r id e s o f th e E le m e n ts u p o n H / D Is o to p e S u b s titu tio n s a n d T h e ir P e rio d ic ity Periodicities are established among the zero-point energy shifts, < 5 (ZPE), of AH" (n =1-4) type hydrides of the elements upon mono H/D isotope substitutions. < 5 (ZPE) for diatomic hydrides is correlated with the position of the element A in the periodic table. The contribution of the A-H stretching force constant to < 5 (ZPE) is to a good approximation a linear function of the square root of the force constant, irrespective of the molecular type. A similar correlation is also found between the square root of the H-A-H bending force constant and its contribution to c)(ZPE). Key words: zero-point energy, H/D isotope substitutions, force constants, periodic table, hydrides of the elements. 
  Reference    Z. Naturforsch. 43a, 511—515 (1988); received January 5 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0511 
 Volume    43 
88Author    Kazumasa Sugiyama, Yoshio Waseda, Keiji Moroishi, Akihisa Inoue, Tsuyoshi MasumotoRequires cookie*
 Title     
 Abstract    t r u c t u r a l S tu d y fo r a N e w S u p e rc o n d u c tin g P h a s e in th e B i-S r-C u -O S y s te m A structural identification of the superconducting phase in the Bi-Sr-Cu-O system has been carried out by X-ray and electron diffraction. A lamellar oxide structure expressed by the formula Bi2(Bi, Sr)2CuOv with the orthorhombic a = 0.537 nm, b ~ 5 ■ 0.537 nm and c = 2.463 nm (pseudo-tetragonal subcell a = 0.5369 (l)nm and c = 2.4627(5) nm) is found to be responsible for the super­ conductive property. The structural model of this compound is compared with the Aurivillius phases. 
  Reference    Z. Naturforsch. 43a, 517—520 (1988); received March 13 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0517 
 Volume    43 
89Author    E. Duffner, A. RieckersRequires cookie*
 Title     
 Abstract    n th e G lo b a l Q u a n tu m D y n a m ic s o f M u lti-L a ttic e S y s te m s w ith N o n -lin e a r C la s s ic a l E f fe c ts * The microscopic dynamics for a class of long range interacting multi-lattice quantum systems is constructed in the thermodynamical limit by means of operator algebraic concepts. By direct estimations the existence of the limiting Schrödinger dynamics is proven for a set of states, which comprises also globally non-equilibrium situations. The expectation values of the classical observ-ables in the pure phase states are shown to satisfy a set of coupled non-linear differential equations. The limiting Heisenberg dynamics is derived as a VF*-automorphism group in the partially universal von Neumann algebra which corresponds to the selected set of states; it is in general, however, not er-weakly continuous in the time parameter. 
  Reference    Z. Naturforsch. 43a, 521—532 (1988); received February 26 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0521 
 Volume    43 
90Author    Dieter PfirschRequires cookie*
 Title      
 Abstract    On the basis of a variational formulation of the Vlasov-Maxwell theory it was recently shown that, for instance, all magnetically confined plasmas allow the existence of negative energy waves. Such waves can become nonlinearly and dissipatively unstable and might therefore be of importance in explaining anomalous transport. The proof of this result uses infinitely strongly localized perturba­ tions. This is, however, not necessary: in this paper it is shown by discussing general, homogeneous, magnetized plasmas that the necessary localization is related to the average gyroradius rg of the relevant particle species. For unstable plasmas the extent or wavelengths of negative energy waves can be of the order of rg, whereas for linearly stable plasmas the extent can be a small fraction of rg. 
  Reference    Z. Naturforsch. 43a, 533—537 (1988); received March 25 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0533 
 Volume    43 
91Author    W. Fink, H. Radkowitsch, E. W. LangRequires cookie*
 Title    in  
 Abstract    U n d e rc o o le d A q u e o u s P o ta s s iu m -a n d C e siu m H a lid e S o lu tio n s Aqueous emulsions of potassium-and cesium halides in cycloalkane mixtures can be undercooled at a pressure of 225 MPa to temperatures around 170K. In these emulsions deuterium spin-lattice relaxation times 7"i have been determined as function of salt concentration, temperature and pressu­ re at magnetic fields of 2.4 Tesla and 7.0 Tesla. The frequency and temperature dependence of the relaxation time curves is described quantitatively within a motional model which is consistent with known local structural features in these solutions. Model parameters deduced are compared with those obtained in related studies of the other alkali-halides, and conclusions are drawn regarding the influence of structure and composition on molecular motions. D e u te ro n S p in -L a ttic e R e la x a tio n T im e s 
  Reference    Z. Naturforsch. 43a, 538—546 (1988); received April 6 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0538 
 Volume    43 
92Author    E. Barbero, C. Miraldi, P. Oldano, Taverna ValabregaRequires cookie*
 Title     
 Abstract    A homogeneously aligned nematic layer with positive dielectric and diamagnetic anisotropies, placed in crossed electric and magnetic fields orthogonal to the undistorted molecular direction, is considered. Following Deuling's procedure, the possible director field configurations are classified into four types or "phases", characterized by distortions which are zero, pure twist, splay-bend and mixed type, respectively. It is shown that the transitions between these phases are generally of second order. Simple approximate expressions relating the critical fields and the distortion angles are given for the limiting cases of very small and very large distortions. The validity ranges of the approxima­ tions are found by comparison with the results of a numerical analysis. The experimental critical lines corresponding to three different types of phase transitions, obtained with a ZLI 1738 sample, are compared with theoretical ones. The agreement between theory and experiment is quite satisfactory. PACS 61.30-v F r e e d e r ic k s z T r a n s itio n s in C ro s s e d E le c tric a n d M a g n e tic F ie ld s 
  Reference    Z. Naturforsch. 43a, 547—554 (1988); received January 23 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0547 
 Volume    43 
93Author    K. Meidenbauer, G. GliemannRequires cookie*
 Title     
 Abstract    ffe c ts o f T e m p e ra tu re a n d M a g n e tic F ie ld s o n th e L u m in e s c e n c e o f S in g le C r y s ta l (N H 4) 2T e C l6 The optical absorption of (NH4)2TeCl6 in acetonitrile at room temperature and the luminescence (spectra, decay curves) of single crystal (NH4)2TeCl6 at 1.9 K < T < 180K and at applied magnetic fields H (0 < H < 6T) are reported. The temperature dependence of the luminescence indicates the existence of a metastable excited state energetically by ~ 80 cm ~1 below a second excited state. With H ||<111> the decay curves are monoexponential with magnetic field dependent slopes. H ||<001> yields biexponential decay curves, each composed of a slow component corresponding to the decay at H = 0, and of a field dependent fast component. The experimental results can be explained by effects of a tetragonal Jahn-Teller distortion due to a strong coupling of the excited electronic state 3TIu of the Te(IV) ions and Eg vibration modes. 
  Reference    Z. Naturforsch. 43a, 555—560 (1988); received March 30 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0555 
 Volume    43 
94Author    B. Kleibömer, D. H. SutterRequires cookie*
 Title     
 Abstract    h e V ib r a tio n a l S t a te D e p e n d e n c e o f th e 14N Q u a d r u p o le C o u p lin g T e n s o r in A n ilin e . A M ic ro w a v e F o u r ie r -T ra n s fo r m S tu d y C o m b in e d w ith S e m irig id B e n d e r C a lc u la tio n s Experimental values for the diagonal elements of the 14N quadrupole coupling tensor derived from analysis of the hyperfine structure of low-J rotational transitions are reported for the two lowest states of the amino wagging mode. They show the expected difference due to averaging over the large amplitude amino wag. A semirigid bender analysis of previously published infrared data provides the inversion angle expectation values for use in a quantum-chemical calculation of the corresponding effective Cou­ lomb field gradients at the nitrogen nucleus. The results are compared to those obtained earlier for the related molecules vinylamine, cyanami-de and ammonia. 
  Reference    Z. Naturforsch. 43a, 561—571 (1988); received March 22 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0561 
 Volume    43 
95Author    S. V. Hannongbua, T. Ishida, E. Spohr, K. HeinzingerRequires cookie*
 Title      
 Abstract    A Molecular Dynamics simulation of a solution of one Li+ in 215 NH3 molecules has been performed at an average temperature of 235 K. A newly developed flexible model for NH3 is employed and the Li + —NH3 interactions are derived from ab initio calculations. The structure of the solution is described by radial distribution functions and the orientation of the molecules. A solvation number of six is found for Li+ and a strong preference of the solvation shell molecules exists for an orientation where the Li + —N vector and the dipole moment direction of NH3 are parallel. The self-diffusion coefficient, the hindered translational motions and librations are calcula­ ted separately for the ammonia molecules in the solvation shell and in the bulk. The effect of Li + on intramolecular geometry and vibrations is reported. M o le c u la r D y n a m ic s S tu d y o f a L ith iu m Io n in A m m o n ia 
  Reference    Z. Naturforsch. 43a, 572—582 (1988); received March 18 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0572 
 Volume    43 
96Author    Dieter Oelkrug, Klaus Rempfer, Ellen Prass, Herbert MeierRequires cookie*
 Title    F Investigations on the Fluorescence of Distyrylbenzenes  
 Abstract    lu o re s z e n z -U n te rs u c h u n g e n a n D is ty ry lb e n z o le n The absorption and fluorescence of three isomeric distyrylbenzenes are investigated as function of temperature. From the fluorescence decay times and fluorescence quantum yields two classes of oligostyrylarenes can be distinguished. A decisive criterion for this classification is, whether the first excited singlet state Sj belongs to an allowed or forbidden transition S0— >Sj. 
  Reference    Z. Naturforsch. 43a, 583—590 (1988); eingegangen am 25. Februar 1988 
  Published    1988 
  Keywords    o-, m-, p-Distyrylbenzenfes, Fluorescence Lifetimes, Fluorescence Quantum Yields, Photoreactivity 
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 Identifier    ZNA-1988-43a-0583 
 Volume    43 
97Author    Ruggero Caminiti, CarmenMunoz Roca, Daniel Beltran-Porter, Antonella RossiRequires cookie*
 Title     
 Abstract    m o rp h o u s C o m p le x e s M M (E D T A) (H 20) 4 • 2 H 20 . L A X S a n d X P S In v e s tig a tio n o f th e L o c a l S tr u c tu r e The amorphous MM(EDTA)(H20)4-2 H20(M = Ni,Co) substances are made up of infinite chains of alternating "hydrated" and "chelated" octahedra bridged by carboxylate groups: M(H20)4 — M(EDTA)-M(H20)4-... . XPS enables to ascertain that the coordination of the EDTA ligand in the amorphous phase is identical to that in the crystalline phase, i.e., hexacoordination toward the M atom and two bridging groups in the Ni —Ni, Co —Co compounds. 
  Reference    Z. Naturforsch. 43a, 591—596 (1988); received February 3 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0591 
 Volume    43 
98Author    OttoL. Stiefvater, Adran Cemeg, Coleg Prifysgol, Gogledd Cymru, Bangor Ll57Requires cookie*
 Title    I. The Doubly Determined Substitution Structure  
 Abstract    Double Resonance Modulation (DRM) microwave spectroscopy has been used to determine the rotational constants of isotopic forms of normal (C2H2N20 2) and perdeuterated furazan (C2D2N20). From these data the complete substitution structures have been derived by Kraitchman methods and by the computer program GEOM. The latter procedure fails to give correct results due to the decrease of the moment of inertia about the C2v-axis and the simultaneous interchange of inertial axes in the 180-3,4-d2-form. The following bondlengths (in Ä) and angles (in degrees) are best compatible with the total body of isotopic information: 0 -N = 1.3729 [6] * NON = 111.15 [8] N -C = 1.3032 [13] £ ONC = 105.53 [5] C -C =1.4211 [9] £ NCC = 108.89 [3] C -H = 1.0763 [5] CCH = 130.16 [3] Here, the uncertainties cover small differences between normal and d2-furazan as well as discrepan­ cies resulting from different schemes of structure calculation. M ic ro w a v e S p e c tr a o f F u r a z a n 
  Reference    Z. Naturforsch. 43a, 597—606 (1988); received March 21 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0597 
 Volume    43 
99Author    OttoL. StiefvaterRequires cookie*
 Title    II. Nuclear Quadrupole Coupling in dj-Furazan  
 Abstract    The nuclear quadrupole coupling constants for the two nitrogen atoms in monodeuterated furazan (C2HDN20) were determined from the hyperfine structure of eight rotational transitions with low J-values. The coupling constants along the inertial axes are: X aa (2) = + 3.546(10) MHz, xaa{5) = -5.044(10) MHz, X bb (2) = -4.690(10) MHz, Xu(5) = + 3.900(10) MHz, X cc (2) = + 1.144(10) MHz, X cc (5) = + 1.144(10) MHz. In conjunction with structural information from the preceding study, these data yield the principal coupling constants, with 3er-uncertainties, as: Zr(2/5) = — 5.53 (4) MHz, Zt(2/5) = + 4.39(4)MHz, Z)r(2/5) = + 1.14(4) MHz. The radial electric field gradients deviate from the direction of the external bisector of the ring angle ONC by 24.6° towards the oxygen atom. These results are in qualitative agreement with previous work by NQR spectroscopy and with the results of ab initio molecular orbital calculations. M ic ro w a v e S p e c tr a o f F u r a z a n 
  Reference    Z. Naturforsch. 43a, 607—613 (1988); received March 21 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0607 
 Volume    43 
100Author    A. M. Habib, M. H. Abdel-Kader, M. A. Salem, S. T. Abdel-HalimRequires cookie*
 Title    Oxidation of a Cyanine Dye with o-Cl-Dibenzoyle Peroxide and Peroxydisulphate  
 Abstract    The oxidation of the cyanine dye l-methyl-4-N-dime-thylamine-y-stilbazolium iodide with o-Cl dibenzoyl perox­ ide and peroxydisulphate ion is kinetically investigated. In both cases the oxidation process obeys second order kinetics, being first order in the oxidant molecule and first order in the cyanine dye. The thermodynamic parame­ ters evaluated for the reaction between the dye and o-Cl-DBP are £a = 45.6 kJ m oljlm, AH* = 43.09 kJ mol" \ and <dS* = — 115.7 Jdeg~1 mol"x. The corresponding values of £a, AH, and AS* obtained for the dye/S2Og 2 system are 58.01 kJmol-1, 55.5 kJ mol-S and -147.8 Jdeg"1 mol"l. Proposed mechanisms are discussed. Key words: Oxidation of cyanine dyes, peroxydisulphate and organic peroxides. recorded with a uv/vis Pye Unicam SP 8000 spectrophoto­ meter. The solvent was ethanol in case of syanine/o-Cl-DBP and water in case of cyanine/S2Og The second method was used for the evaluation of the "kinetic order for the oxidants. This was done iodometrically following the procedure re­ ported by Kolthoff and Carr [7], 0.8 0.6 C U 0.2 0.0 2(min) "'"'f... 5 . \ 10 ^ —15 \ 20 Jm ^ ^ ^ r ^ 25 y j i i i 325 350 400 450 Wavelength ---500 550 Fig. 1. The change in the absorbance of cyanine dye during the reaction with o-Cl-DBP at 50°C in ethanol. 
  Reference    Z. Naturforsch. 43a, 614—616 (1988); received March 31 1988 
  Published    1988 
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 Identifier    ZNA-1988-43a-0614_n 
 Volume    43 
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