| | 82 | Author
| Toshiyuki Takamuku, Mikito Ihara, Toshio Yamaguchi, Hisanobu Wakita | Requires cookie* | | | Title
| Raman Spectroscopic and X-ray Diffraction Studies on Concentrated Aqueous Zinc (II) Bromide Solution at High Temperatures  | | | | Abstract
| Raman and X-ray scattering experiments have been performed on an aqueous zinc (II) bromide solution with molar ratio [H20]/[ZnBr2] = 10 at 25 to 140 °C. The intensity of the totally symmetric Zn-Br stretching vibration (v^ for the dibromozinc(II) complex increased with increasing temper-ature while that for the tetrabromo complex decreased. A broad band assigned to the symmetric Zn-O stretching vibration (vj for the aqua zinc (I I) ion decreased in intensity with increasing temperature. The X-ray diffraction data revealed that the average number of the Zn-Br interactions within the zinc (II) bromo complexes does not change with temperature, whereas the number of Br • • • Br nonbonding interactions within the complexes decreases from 1.8 at 25 °C to 1.5 at 100 °C. From both Raman and X-ray data it is concluded that with increasing temperature the dibromo species is favored, whereas the tetrabromo and aqua zinc(II) species are unstable in the solution. The analysis of the X-ray diffraction data has shown that the mean Zn-Br bond length within the zinc (II) bromo complexes shortens gradually with increasing temperature, accompanied with an increase in the interligand Br • • • Br distance. This finding suggests that the Br-Zn-Br bond angle increases with decreasing Zn-Br distance for the lower zinc(II) bromo complexes. The equilibrium shift of the zinc (II) bromo complexes with temperature is discussed on the basis of ion-ion, ion-water, and water-water interactions. | | | |
Reference
| Z. Naturforsch. 47a, 485—492 (1992); received November 27 1991 | | | |
Published
| 1992 | | | |
Keywords
| Raman spectroscopy, X-ray diffraction, Zinc(II)bromide, High temperature, Solution structure | | | |
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| default:Reihe_A/47/ZNA-1992-47a-0485.pdf | | | | Identifier
| ZNA-1992-47a-0485 | | | | Volume
| 47 | |
| 83 | Author
| Alexander Apelblat, Josef Barthel | Requires cookie* | | | Title
| Conductance Studies of Aqueous Succinic Acid | | | | Abstract
| Conductance measurements of aqueous solutions of succinic acid and of di-sodium succinate were performed from 278.15 to 308.15 K and the limiting conductances A 0 (1/2 Succ 2-) are reported. The Waiden product is independent of temperature: A 0 (1/2 Succ 2 ~) • >/(T) = 0.503 ± 0.001. The salt con-ductances closely obey the Onsager limiting law. The evaluation of the equilibrium constants for the primary and secondary steps of dissociation, K l and K 2 , and the limiting conductances of the hydrosuccinate ion, (HSucc -), are discussed using the Quint and Viallard conductance equation. | | | |
Reference
| Z. Naturforsch. 47a, 493—498 (1992); received November 2 1991 | | | |
Published
| 1992 | | | |
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| default:Reihe_A/47/ZNA-1992-47a-0493.pdf | | | | Identifier
| ZNA-1992-47a-0493 | | | | Volume
| 47 | |
| 85 | Author
| N. Heineking, J. Gripp, H. Dreizler | Requires cookie* | | | Title
| Bromine Spin-Rotation Coupling Constants of Cyclopropylbromide-79 Br and -81 Br | | | | Abstract
| We reinvestigated the microwave spectrum of cyclopropylbromide with the increased resolution of pulsed microwave Fourier transform spectroscopy. Because of the higher frequency precision, it was possible to determine the spin-rotation coupling constants of bromine. Global fits of rotational constants, quartic centrifugal distortion constants, quadrupole coupling constants including the off-diagonal component x ac > spin-rotation coupling constants simultaneously to almost one hundred hyperfine components for each of the two bromine isotopomers resulted in overall standard deviations of well below 5 kHz. | | | |
Reference
| Z. Naturforsch. 47a, 507—510 (1992); received November 11 1991 | | | |
Published
| 1992 | | | |
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| default:Reihe_A/47/ZNA-1992-47a-0507.pdf | | | | Identifier
| ZNA-1992-47a-0507 | | | | Volume
| 47 | |
| 86 | Author
| N. Heineking, H. Dreizler | Requires cookie* | | | Title
| Nuclear Quadrupole Hyperfine Structure in the Rotational a Q 1 -Subbranch of Deuteroisothiocyanic Acid, DNCS | | | | Abstract
| The two-nuclei quadrupole hyperfine structure of four a Q!-subbranch transitions of deuteroiso-thiocyanic acid, DNCS, has been resolved and analyzed by use of a waveguide microwave Fourier transform spectrometer. The analysis yielded one previously unknown quadrupole coupling con-stant (X-=Xbb-Xcc) for both nitrogen (x N -= +27.6(11) kHz) and deuterium X-= +175.8(11) kHz). Taking into account the results from earlier work on HNCS, DNCS, HNCO, and DNCO, the orientations of the principal axis systems of the two quadrupole coupling tensors could be calculated. It appears that while the deuterium tensor is aligned to the D-N internuclear axis as expected, the nitrogen tensor is tilted away from the bisector of the DNC angle by 13° towards the NCS chain. | | | |
Reference
| Z. Naturforsch. 47a, 511—514 (1992); received January 2 1991 | | | |
Published
| 1992 | | | |
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| default:Reihe_A/47/ZNA-1992-47a-0511.pdf | | | | Identifier
| ZNA-1992-47a-0511 | | | | Volume
| 47 | |
| 93 | Author
| F. Winterberg | Requires cookie* | | | Title
| On the Problem of a Finitistic Quantum Field Theory | | | | Abstract
| A finitistic quantum field theory, as a model for a unified theory of elementary particles is proposed, making the assumption that all spatial and temporal distances can only assume integer values of a fundamental length and time, for which we have chosen the Planck length and Planck time. To satisfy the condition of causality in its quantized version, the theory must be exactly nonrelativistic, because only then can the concept that points in space are separated by multiples of a fundamental length be formulated in an invariant way. The theory is formulated as a partial finite difference equation, invariant under translations and rotations in space, and translations in time, and can be expressed as a partial differential equation of infinite order. The theory is free of all divergen-cies, has a positive definite metric in Hilbert space and therefore no ghost states. Possessing a fundamental length, chosen to be equal the Planck length, the theory has an inbuilt cut-off at the Planck energy. For energies sufficiently below the Planck energy, the theory can be approximated by the previously described Planck aether model, which can be viewed as a superfluid consisting of Planck masses, leading to special relativity as a dynamic symmetry in the asymptotic limit of low energies. | | | |
Reference
| Z. Naturforsch. 47a, 545—553 (1992); received June 151991 revised version received January 101992 | | | |
Published
| 1992 | | | |
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| default:Reihe_A/47/ZNA-1992-47a-0545.pdf | | | | Identifier
| ZNA-1992-47a-0545 | | | | Volume
| 47 | |
| 94 | Author
| B. S. Dandapat, B. P. Kumar | Requires cookie* | | | Title
| Onset of Thermosolutal Convection in a Liquid Layer Having Deformable Free Surface -I. Stationary Convection | | | | Abstract
| The effect of surface deformation on the onset of thermosolutal convection in a horizontal thin layer heated from below and salted from above is examined, using linear stability theory. It is found that two critical Crispation numbers C^ and Cr 2 exist. For Cr 5S C^ the instability mechanism remains unefTected by the deformation of the free surface, whereas for Cr 1 <Cr<Cr 2 the critical Marangoni number (M c) decreases, showing instability due to deformation. If Cr = Cr 2 , M c is obtained for two values of the wave number. When Cr>Cr 2 , M c decreases as the wave number tends to zero. Further, the effect of the Marangoni number, Biot number, Bond number etc. on the stability characteristics of the problem is discussed. | | | |
Reference
| Z. Naturforsch. 47a, 554—560 (1992); received September 4 1991 | | | |
Published
| 1992 | | | |
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| default:Reihe_A/47/ZNA-1992-47a-0554.pdf | | | | Identifier
| ZNA-1992-47a-0554 | | | | Volume
| 47 | |
| 95 | Author
| B. S. Dandapat, B. P. Kumar | Requires cookie* | | | Title
| Onset of Thermosolutal Convection in a Liquid Layer Having Deformable Free Surface -II. Overstability | | | | Abstract
| The onset of thermosolutal convection driven by a temperature and concentration dependent surface tension is investigated for a thin layer of fluid having a deformable free surface. It is shown that there exist two Crispation numbers (Cr) for oscillatory modes of instability. It is further shown that Cr and the frequency of the oscillatory mode are strongly coupled for large values of Cr. It is found that Cr destabilizes the system for both cases, salted from below and salted from above. | | | |
Reference
| Z. Naturforsch. 47a, 561—564 (1992); received January 10 1992 | | | |
Published
| 1992 | | | |
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| default:Reihe_A/47/ZNA-1992-47a-0561.pdf | | | | Identifier
| ZNA-1992-47a-0561 | | | | Volume
| 47 | |
| 96 | Author
| A. Chrzanowska, K. Sokalski | Requires cookie* | | | Title
| Static and Hydrodynamic Properties of Nematic Liquid Crystals | | | | Abstract
| The static properties of nematic liquid crystals are summarized. The mean field potential emerging from the static distribution function has been used to the hydrodynamic theory. Rotational viscosity coefficients have been investigated. The Parodi relation has been shown to be completely satisfied. Static and hydrodynamic properties have been predicted on the basis of one intermolecular poten-tial. | | | |
Reference
| Z. Naturforsch. 47a, 565—572 (1992); received January 8 1992 | | | |
Published
| 1992 | | | |
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| default:Reihe_A/47/ZNA-1992-47a-0565.pdf | | | | Identifier
| ZNA-1992-47a-0565 | | | | Volume
| 47 | |
| 97 | Author
| H. Krause, D. H. Sutter | Requires cookie* | | | Title
| E H-N = CH-C = N +0 Z H-N = CH-C = N | | | | Abstract
| The 14 N hyperfine multiplets of low-7 rotational transitions of the E and Z isomers of HN = CH — C = N, produced by flash pyrolysis from (CH 3) 2 N —C = N as precursor, were observed and analysed. The quadrupole coupling constants determined are (c-axis perpendicular to the molecular plane): , X aa /MHz XJUWz XJUHz E H — N = CH — C = N -4. The observed hfs multiplets were predicted with reasonable accuracy from RHF/6-311G** field gradients, once the latter had been scaled appropriately to compensate partly for the typical errors in the RHF-wave functions. The hitherto unmeasured 14 N hyperfine multiplets of the related pyruvonitriles, H —N = C(CH 3) —C = N, are predicted. | | | |
Reference
| Z. Naturforsch. 47a, 573—582 (1992); received December 17 1991 | | | |
Published
| 1992 | | | |
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| default:Reihe_A/47/ZNA-1992-47a-0573.pdf | | | | Identifier
| ZNA-1992-47a-0573 | | | | Volume
| 47 | |
| 98 | Author
| Vytautas Balevicius, Norbert Weiden, Alarich Weiss | Requires cookie* | | | Title
| *H and 2 H NMR Studies of Mixtures 2,6-Lutidine/Water Near the Lower Critical Solution Point | | | | Abstract
| Deuteron spin-lattice relaxation time (TJ measurements of binary mixtures 2,6-lutidine/D 2 0 have been done near the lower critical solution point (T c L), e = (T — T g L)/T c 10~ 5 . Singularities are observed at T c L . The changes in the slope of Ti (2 H) =/(T) can be interpreted as due to the effect of concentration changes on T y and simultaneously strong overlaping of 2 H NMR signals from coexisting phases. In the two-phase region, ca. 2°C above T c L two D 2 0 signals with very strong temperature evolution have been detected. Similar doubling of 2,6-lutidine 'H NMR signals has been observed already at T — T c L ^ 1 °C. It is shown that the two signals arise from the nuclei in two coexisting phases; they are not due to pecularities of hydrogen bond. The difference between chemical shifts of both D 2 0 signals ö' — ö" possess the property of an order parameter, i.e. ö' — (5"~ e ß with 0 = 0.336 ±0.030. | | | |
Reference
| Z. Naturforsch. 47a, 583—587 (1992); received December 28 1991 | | | |
Published
| 1992 | | | |
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| default:Reihe_A/47/ZNA-1992-47a-0583.pdf | | | | Identifier
| ZNA-1992-47a-0583 | | | | Volume
| 47 | |
| 99 | Author
| H. Harder, A. G. Lesarri, J. L. Alonso, H. Dreizler, J. C. López | Requires cookie* | | | Title
| Determination of the Ring-Inversion Barrier in y-Thiobutyrolactone by Microwave Fourier Transform Spectroscopy | | | | Abstract
| The microwave spectrum of y-thiobutyrolactone has been reinvestigated using microwave Fourier transform spectroscopy. The /i c rotation inversion transitions have been found to be splitted for the first excited state of the vibration at ~ 250 cm -1 . An inversion splitting of 0.014 MHz has been measured directly from these transitions. These splittings indicate that the vibration is related to a double minimum potential function describing two ring-twisted conformations connected by inver-sion. A one-dimensional reduced potential function has been derived for this vibration and gives a barrier to ring inversion of 1380± 350 cm" \ | | | |
Reference
| Z. Naturforsch. 47a, 588—590 (1992); received January 20 1992 | | | |
Published
| 1992 | | | |
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| default:Reihe_A/47/ZNA-1992-47a-0588.pdf | | | | Identifier
| ZNA-1992-47a-0588 | | | | Volume
| 47 | |
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