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1989 (196)
161Author    D. LortzRequires cookie*
 Title      
 Abstract    It is shown that a small anisotropy of the magnetic diffusivity tensor admits stationary axisym­ metric solutions of the kinetic dynamo problem. For the case of a large aspect ratio the solutions can be expressed explicitly in terms of elementary functions. A x is y m m e tric D y n a m o S o lu tio n s 
  Reference    Z. Naturforsch. 44a, 1041—1045 (1989); received July 22. 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1041 
 Volume    44 
162Author    J. J. Parisi, R. P. Peinke, Huebener, M. Duong-VanRequires cookie*
 Title      
 Abstract    We study the cooperative spatio-temporal behavior of semiconductor breakdown via both prob­ abilistic and dynamical characterization methods (fractal dimensions, entropies, Lyapunov expo­ nents, and the corresponding scaling functions). Agreement between the results obtained from the different numerical concepts (e.g., verification of the Kaplan-Yorke conjecture and the Newhouse-Ruelle-Takens theorem) gives a self-consistent picture of the physical situation investigated. As a consequence, the affirmed chaotic hierarchy of generalized horseshoe-type strange attractors may be ascribed to weak nonlinear coupling between competing localized oscillation centers intrinsic to the present semiconductor system. 
  Reference    Z. Naturforsch. 44a, 1046—1050 (1989); received July 13 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1046 
 Volume    44 
163Author    JonathanO P Barut, DowlingRequires cookie*
 Title     
 Abstract    A recently advanced theory of quantum electrodynamics which is not second quantized, but rather based on self-fields is adopted to a relativistic calculation of (<7-2). In analogy to classical electrodynamics, radiative corrections are seen as arising from the back reaction of the self-field upon the source. Vacuum field fluctuations, assumed to be the physical cause of radiative correction in standard QED. are absent in the present self-field approach, which recently has been applied to calculate spontaneous emission, Lamb shift, vacuum polarization, and to a non-relativistic calcula­ tion of {g-2), all in free space as well as in cavities. We conclude that the self-field of the electron can be consistently considered to be the physical origin of all radiative processes, as an alternative picture to hypothetical vacuum fluctuations., Second quantization. Q E D B a se d on S e lf-F ie ld s : A R e la tiv is tic C a lc u la tio n o f g -2. 
  Reference    Z. Naturforsch. 44a, 1051—1055 (1989); received July 8 1989 
  Published    1989 
  Keywords    Quantum electrodynamics, Self-fields, g-2 
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 Identifier    ZNA-1989-44a-1051 
 Volume    44 
164Author    U. Riedl, G. GliemannRequires cookie*
 Title     
 Abstract    le c tro n ic S p e c tr a o f S in g le -C r y s ta l M a le o n itr ile d ith io la te C o m p le x e s o f Irid iu m (1): [ I r (C O) 2 m n t| T B A (m n t = [ S 2C 2 (C N) 2] 2 -; T B A = |(C 4H 9) 4 N1 +) The polarized optical absorption and emission (spectra, decay times) of single-crystal [lr(CO)2mnt] TBA at temperatures 2 K^ T<295 K and homogeneous magnetic fields O^H ^ 6T are reported. The highly resolved spectra show 0-0 transitions with vibrational satellites and phonon side bands. Applied magnetic fields yield no effect on the emission. The lowest excited electronic states can be assigned to the spin-orbit components A\, B\, and B\ of the charge transfer triplet 3A2 (symmetry C2l.). 
  Reference    Z. Naturforsch. 44a, 1057 (1989); received July 18 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1057 
 Volume    44 
165Author    H. Krause, D. H. Sutter, MichaelH. PalmerRequires cookie*
 Title    I. Methanimine, its Molecular ^-Tensor, its M agnetic Susceptibility Anisotropics, its Molecular Electric Quadrupole Moment, its Electric Field Gradient at the Nitrogen Nucleus, and its Nitrogen Spin-Rotation Coupling  
 Abstract    The rotational Zeeman effect has been observed in methanimine which was produced from ethylenediamine by flash pyrolysis. The observed vibronic ground state expectation values of the molecular g-values, the magnetic susceptibility anisotropies and the molecular electric quadrupole moments are: gaa = -1.27099(22), gbb= -0.18975(7), gcc= -0.03440(8), 2caa-Qbh-Qcc = 12.49(19) • 10~6ergG-2mor \ 2Qbb-L c-Qaa = 5.22(11) • 10"6ergG~2 mol" \ Qua = 0.43(17) • 10~26esu cm2, Qbb= 1.08(10) • IO"26 esu cm2, and Qcc= -1.51 (26) ■ IO"26 esu cm2. With the TZVP ab initio value for the out-off plane electronic second moment as additional input, reliable values can be given also for the individual components of the magnetic susceptibility tensor and for the bulk susceptibility: t = ({.a + Zib + Zcc)ß=-13.13(88) • 10"6 erg G -2 m o l1. From low-J a-and b-type zero field transitions the spin-rotation coupling constants and the 14N nuclear quadrupole coupling constants could be redetermined with improved accuracy. These data are compared with our new theoretical results. 
  Reference    Z. Naturforsch. 44a, 1063—1078 (1989); received July 25 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1063 
 Volume    44 
166Author    N. 15n, M.C L Gerry, N. Heineking, H. Mäder, H. DreizlerRequires cookie*
 Title     
 Abstract    e s o lu tio n o f th e 14N N u c le a r Q u a d r u p o le H y p e r fin e S tr u c tu r e in th e R o ta tio n a l S p e c tru m o f H y d r a z o ic A c id , H N 3 , a n d E v a lu a tio n o f th e R o ta tio n a l C o n s ta n ts o f H 1SN N N a n d Microwave Fourier transform spectra have been measured for hydrazoic acid as its normal isotopomer, H14N3, and two substituted isotopomers, H15N14N14N and H14N14N15N. The 14N quadrupole hyperfine structure has been resolved in all cases, and the quadrupole coupling constants of all N atoms have been determined. They are compared with those from ab initio predictions. Rotational constants A have been evaluated accurately for the first time for the two 15N species, and have been used to confirm a previously published structure. 
  Reference    Z. Naturforsch. 44a, 1079—1086 (1989); received August 12 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1079 
 Volume    44 
167Author    J. Spieckermann, D. H. SutterRequires cookie*
 Title     
 Abstract    e th y l N i t r a t e , its M o le c u la r g -V alues, M a g n e tic S u s c e p tib ility A n is o tro p ie s , M o le c u la r E le c tric Q u a d r u p o le M o m e n t, S e c o n d M o m e n ts o f th e E le c tro n ic C h a r g e D is trib u tio n , a n d E le c tric F ie ld G r a d ie n t a t th e N itro g e n N u c le u s The high field molecular Zeeman effect of low-J rotational transitions has been observed in methyl nitrate. The spectrum is complicated by the presence of the small 14N nuclear quadrupole coupling. Methyl top internal rotating splitting is negligible in the transitions studied here. From line shape analyses the individual satellite frequencies in the Zeeman-hfs-multiplets could be determined with experimental uncertainties typically smaller than ±2 kHz. The molecular Zeeman parameters and the 14N nitrogen coupling constants were fitted simultaneously to the observed splittings. The molecular c/-values are gaa = —0.1168(5), gbb= —0.0449(3), and gcc= —0.0235(4). The molecular mag­ netic susceptibility anisotropies in units of IO-6 erg gauss-2 mol-1 are 2Q aa —Zbb —Q cc = + 1.24(54) and 2£bb — £cc — £aa = +\3.\4(53). The 14N nuclear quadrupole coupling constants are yaa — + 0.308(17) MHz, X bh — Xcc— —0.262(31) MHz. The molecular electric quadrupole moments calcu­ lated from the observed rotational constants and Zeeman parameters in units of 10"26 esu cm2 are Q = +3.4(6), Qbb— —4.6(6), and Qcc— +1.2(10). Knowledge of the molecular structure and the molecular ^-values also gives the diagonal elements in the paramagnetic susceptibility tensor and the ansiotropies in the second moments of the electronic charge distribution. The results in units of 10"6 era gauss"2 mole-1 are qp a = + 118.14(10), +279.73(14), and +357.40(26), and (a2) -(b ') = + 37.14(14) Ä2, </>*>-<c2>= +20.46(22) Ä2, and <cf> —<a2>= —57.60(21) Ä2. 
  Reference    Z. Naturforsch. 44a, 1087—1096 (1989); received August 12 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1087 
 Volume    44 
168Author    Requires cookie*
 Title     
 Abstract    lg e b ra ic S tu d ie s o f K e k u le S tr u c tu r e s . A S e m ila ttic e B a s e d on th e S e x te t R o ta tio n C o n c e p t 
  Reference    Z. Naturforsch. 44a, 1097 (1989) 
  Published    1989 
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 Identifier    ZNA-1989-44a-1097 
 Volume    44 
169Author    R. Zaleski, Z. Jakubas, L. Galewski, SobczykRequires cookie*
 Title      
 Abstract    Dielectric. DSC and preliminary X-ray diffraction studies on [(C2H5)4N]3Sb2Br9 (TEABA) and [(C2H5)4N]3Bi2Br9 (TEABB) are reported. The compounds are isomorphous, space group P6322. The static electric permittivity measurements on single crystals in the temperature range 220 290 K revealed that both compounds show two distinct dielectric anomalies; TEABA at Tcl = 258 K and Tc2 = 252 K, while TEABB at Tcl= 265 K and Tcl = 248 K. The DSC studies show only one anomaly of first order at TcX =258 K for TEABA, and TcX =266 K for TEABB. These transitions are pre­ sumably related to a freezing of the reorientational motion of the tetraethylammonium cations. S tr u c tu r a l P h a s e T ra n s itio n s in |(C 2H 5)4N ] 3S b 2B r 9 a n d |(C 2H 5) 4N |3B i2B r 9 
  Reference    Z. Naturforsch. 44a, 1102 (1989); received May 11 1989 
  Published    1989 
  Keywords    Alkylammonium halogenoantimonates, Bismuthates, Phase transition Dielectric, DSC, Single crystals 
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 Identifier    ZNA-1989-44a-1102 
 Volume    44 
170Author    GeroldPeter Baier, Klaus Urban, WegmannRequires cookie*
 Title      
 Abstract    We investigate the dynamics of a reaction-diffusion-convection enzyme system as a function of relevant parameters and observe reproducible types of periodic and aperiodic oscillations. These oscillations arise within a narrow diffusion layer only. Some implications for more complex reaction networks are considered. Key words: Enzyme kinetics. Reaction-diffusion-convection system. Oscillation, Chaos, Diffu­ sion layer. D y n a m ic a l In s ta b ilitie s in a D iffu sio n L a y e r 
  Reference    Z. Naturforsch. 44a, 1107 (1989); received July 20 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1107 
 Volume    44 
171Author    Reiko Watanabe, Tetsuo Asaji, Yoshihiro Furukawa, Daiyu Nakamura, Ryuichi IkedaRequires cookie*
 Title     
 Abstract    tr u c tu r a l P h a s e T r a n s itio n s a n d C a tio n ic M o tio n s in P y rid in iu m D ic h lo r o io d a te (I) a s S tu d ie d by l H N M R , D iffe re n tia l T h e r m a l A n a ly s is , a n d P o w d e r X -R a y D iffra c tio n For crystals of pyridinium dichloroiodate(I), (pyH)ICl,, the temperature dependences of the 'H NMR spin-lattice relaxation time Tx and the 'H second moment M2 were determined. M2 was found to be small (~ 1 G2) above room temperature, indicating that the cations perform rapid reorientational motion about their pseudohexad axis perpendicular to the cationic plane. 'H Tx at its minimum was unusually long, indicating this motion occurring in the low symmetry local environments. Phase transitions between stable solid phases were revealed at 282 and 373 K by the 'H NMR measurements and differential thermal analysis. The highest-temperature phase was easily supercooled and transformed reversibly into another metastable phase and back on cooling and warming at almost the same temperature of 138 K. The kinetics of the phase transition from the supercooled to the stable phase at room temperature was analyzed using an Avrami type relation. The growth time of the stable phase was estimated to be about 14 h at room temperature. 
  Reference    Z. Naturforsch. 44a, 1111 (1989); received July 24 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1111 
 Volume    44 
172Author    M. Zander, RiitgerswerkeAg CastropRequires cookie*
 Title    T h e I n tr a -a n  
 Abstract    n u la r I n te r n a l H e a v y -a to m E ffe c t o n th e F lu o re s c e n c e a n d P h o s p h o re s c e n c e P r o p e rtie s o f O x y g e n , S u lp h u r o r S e le n iu m C o n ta in in g H e te ro c y c lic S y s te m s R e la te d to D ib e n z o |b ,n ] p e r y le n e Fluorescence and phosphorescence properties of dibenzo[2,3:10.11] perylo[1.12-bcd] furan (1), dibenzo [2,3:10,11 ] perylo [1,12-bcd] thiophene (2), and dibenzo [2,3:10.11 ] perylo [1.12-bcd] selenophene (3) have been studied. Fluorescence quantum yields as well as phosphorescence lifetimes correlate linearly with £ c* £2 where ck are the Hückel AÖ coefficients in the HOMO of the parent carbocyclic system dibenzo [b. n] perylene (4) on carbon centres k to which the hetero-atom is bound, and £ is the spin-orbit coupling constant of the heavy-atom present. The half-value concentration of fluores­ cence quenching (quencher: methyl iodide) of 1 3 increases with increasing strength of the internal heavy-atom effect present. 
  Reference    Z. Naturforsch. 44a, 1116—1118 (1989); received August 31. 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1116 
 Volume    44 
173Author    H. Frerichs, R. M. Koch, H. Tappe, Gg, WagnerRequires cookie*
 Title      
 Abstract    v e s tig a tio n o f th e R e a c tio n o f N a p h th a le n e w ith 0 (3P) in th e G a s P h a s e The rate of the reaction between naphthalene and atomic oxygen in the electronic ground state was determined in a discharge flow system with mass spectrometric detection for temperatures between 362 and 773 K. All measurements were performed in an excess of O atoms over hydrocar­ bon. The second order rate constant was determined to be (909 + 196 \ , , , k(T) = (1.14 + 0.87) • 10 exp (------— j cm3 moP 1 s"1. Kinetic data are compared with data about the reactions of other aromatic substances and atomic oxygen in the ground state. Some possible reaction channels are discussed. 
  Reference    Z. Naturforsch. 44a, 1119 (1989); received August 26 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1119 
 Volume    44 
174Author    Yoshihiro Furukawa, Daiyu NakamuraRequires cookie*
 Title    C a tio  
 Abstract    n ic D y n a m ic s in th e C r y s ta llin e P h a s e s o f (C H 3N H 3) P b X 3 (X : C I, B r) a s S tu d ie d by P r o to n M a g n e tic R e s o n a n c e T e c h n iq u e s The temperature dependences of the 'H spin-lattice relaxation time Tx, the linewidth parameter 7*. and the second moment M2 of 'H NMR absorption were measured for solid (CH3NH3)PbX3 (X: CI. Br). In the room-temperature cubic phases of both salts, and also in the high-temperature tetragonal phase of (CH3NH3)PbBr3, the cations undergo rapid overall rotation or reorientation. In the lowest-temperature phase of both salts the orientation of the cations is fixed but rapid C3 reorientation of the CH3 and NH3 groups of the cations about their C N bond axes takes place. From the M2 measurements, a precessional motion of the cations in the intermediate-temperature phase of both complexes is suggested. Above room temperature, 1H Tx of both salts can be explained by assuming spin-rotational relaxation operative due to the rapid rotation of the cations. An anomalous behavior of 'H T,, attributable to cross relaxation between 'H and H1Br nuclei, was detected for (CH3NH3)PbBr3 when 7, was measured at 42 MHz. 
  Reference    Z. Naturforsch. 44a, 1122 (1989); received September 5 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1122 
 Volume    44 
175Author    H. Stegemeyer, K. Siemensmeyer, W. Sucrowt, L. AppelRequires cookie*
 Title     
 Abstract    iq u id C r y s ta llin e N o r c h o le s te r y le s te r s : In flu e n c e o f th e A x ia l M e th y lg ro u p s o n th e P h a s e T r a n s itio n s a n d th e C h o le s te r ic H e lix In commemoration of the deceased W. J. A. Goossens Liquid crystalline norcholesteryl anisic esters were prepared in which the methylgroups 19, 21, 27, and 18 are removed successively from the cholestene skeleton. The influence of the axial methylgroups on the phase transition temperatures and the choleric helical structure has been investigated. On heating the 18.19.21.27-tetranorcholesteryl ester, at 155 C an inversion of the helical screw sense from left to right was observed. 
  Reference    Z. Naturforsch. 44a, 1127 (1989); received August 21. 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1127 
 Volume    44 
176Author    Akira Endoh, Isao OkadaRequires cookie*
 Title     
 Abstract    f th e E u te c tic C o m p o s itio n R e fle c tin g th e C h e m la E ffe c t fo r th e I n te r n a l M o b ilitie s Molecular dynamics (MD) simulation has been performed on molten (Li, Na, K)C1 of nearly the eutectic composition at 773 K, 873 K and 973 K. The employed pair potential parameters are based on the Tosi-Fumi ones except the softness parameter, which is somewhat modified. The self-exchange velocities (SEV's) of Li + , Na+ and K+ with reference to CP have been calculated. The sequence of the internal mobilities of these cations is well reproduced by the corresponding SEV's, v; that is vLi < vK < vN a at 773 K, uLi < vN a = rK at 873 K and vLi < vNa < vK at 973 K. S e lf-E x c h a n g e V e lo c itie s in M o lte n (L i, N a , K)C I 
  Reference    Z. Naturforsch. 44a, 1131—1136 (1989); received August 21 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1131 
 Volume    44 
177Author    Fevzi Büyükkiliç, Dogan DemirhanRequires cookie*
 Title    Large-/V Expansion for a Nucleon-Nucleon Potential  
 Abstract    The Schrödinger equation has been solved by \/N expan­ sion for a two nucleon system which interacts by an attrac­ tive Yukawa potential. For the ground and first excited states, energy eigenvalues have been obtained. 
  Reference    Z. Naturforsch. 44a, 1137—1138 (1989); received March 12 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1137_n 
 Volume    44 
178Author    E. Schöll, H. Naber, J. Parisi, B. Röhricht, J. PeinkeRequires cookie*
 Title     
 Abstract    e so n a n c e T ra n sitio n o f th e S p a tia l C o r r e la tio n F a c to r o f S e lf-G e n e ra te d O s c illa tio n s in th e P o s tb re a k d o w n R e g im e o f p -G e The linear correlation factor of spatially coupled nonlinear self-generated oscillations in the post-breakdown regime of p-Gc at 4.2 K is investigated. The observed results can be consistently explained in terms of a two-cell model of energy relaxation oscillations, which yields resonance transitions between correlated and anticorrelated oscillations. These are due to node-focus transi­ tions of the fixed point of the passive cell which is slaved by the active cell. 
  Reference    Z. Naturforsch. 44a, 1139 (1989); received October 5 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1139 
 Volume    44 
179Author    F. WinterbergRequires cookie*
 Title     
 Abstract    u b s tr a tu m I n te r p r e ta t io n o f th e S a g n a c -a n d th e A h a ro n o v -B o h m E ffe c t It is shown that a substratum interpretation reveals a close relationship between the Sagnac-and the Aharonov-Bohm-effect. The characteristic peculiarity of the Aharonov-Bohm-effect, to produce a phase shift of the electron wave function even in the absence of any electromagnetic force fields, can be duplicated by a thought experiment for light waves in the gravitational field of a massive rotating cylinder, which demonstrates that the somewhat similar Sagnac-effect is not caused by centrifugal and Corioli's forces, as it is sometimes claimed. In the substratum interpretation, both the Sagnac and Aharonov-Bohm effect find their explana­ tion in a rotational motion of the substratum. If the substratum flow is irrotational, having the form of a potential vortex, these effects persist even though there are no force fields present. 
  Reference    Z. Naturforsch. 44a, 1145 (1989); received July 7 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1145 
 Volume    44 
180Author    Ján Weis, Ivan Frollo, Luboš BudinskýRequires cookie*
 Title      
 Abstract    Magnetic field inhomogeneities cause blurring and distortion of images gained by nuclear mag­ netic resonance. In order to adjust the magnetic coils finely, a precise and rapid method for measuring the magnetic field is needed. We describe a gradient echo technique of the FLASH version for mapping static magnetic fields. 
  Reference    Z. Naturforsch. 44a, 1151—1154 (1989); received July 14. 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1151 
 Volume    44 
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