| | 1 | Author
| J. Wąsicki, Z. Pająk, A. Kozak | Requires cookie* | | | Title
| Cation and Anion Reorientation at Phase Transition in Pyridinium Tetrafluoroborate  | | | | Abstract
| Temperature dependences of and 19 F second moment and spin-lattice relaxation times for polycrystalline pyridinium tetrafluoroborate were measured. A phase transition was discovered at 202 K. A model of cation reorientation between inequivalent (low-temperature phase) and equiva-lent (high-temperature phase) equilibrium positions is proposed. Whether the anion reorients isotropically or about a symmetry axis cannot be decided. An analysis of cross-relaxation effects yielded activation parameters for cation and anion reorientation. The rotational correlation times for both ions converge just at the phase transition reaching the value of 10~ 10 s. | | | |
Reference
| Z. Naturforsch. 45a, 33—36 (1990); received August 5 1989 | | | |
Published
| 1990 | | | |
Keywords
| NMR, cross-relaxation, molecular motions, phase transitions | | | |
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| default:Reihe_A/45/ZNA-1990-45a-0033.pdf | | | | Identifier
| ZNA-1990-45a-0033 | | | | Volume
| 45 | |
| 2 | Author
| Z. Szafrańska, A. Pająk, Kozak | Requires cookie* | | | Title
| B | | | | Abstract
| Proton and fluorine NMR second moments and spin-lattice relaxation times for polycrystalline tetrabutylammonium tetrafluoroborate have been measured over a wide range of temperatures at several Larmor frequencies. An analysis of cross-relaxation effects results in a determination of activation parameters for anion and cation reorientations. Three solid phases characterized by different ion dynamics are evidenced. M o le c u la r M o tio n in S o lid T e tra b u ty la m m o n iu m T e tr a f lu o r o b o r a te | | | |
Reference
| Z. Naturforsch. 46a, 545—550 (1991); received March 14 1991 | | | |
Published
| 1991 | | | |
Keywords
| NMR, Cross-relaxation, Molecular motions, Phase transitions | | | |
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| default:Reihe_A/46/ZNA-1991-46a-0545.pdf | | | | Identifier
| ZNA-1991-46a-0545 | | | | Volume
| 46 | |
| 3 | Author
| David Stephenson | Requires cookie* | | | Title
| Two-dimensional Two Contact Double Resonance Spectroscopy | | | | Abstract
| A two-dimensional spectroscopic technique is presented. Application of the technique to de-termine all the relaxation rates for a multi-level quadrupole system is discussed along with ex-perimental requirements. Theoretical and experimental data are analyzed for the 14 N, three level, spin 1 system. The analysis shows that all three relaxation rates can be obtained from a single two-dimensional spectrum, and that only 3 peaks in the 3 x 3 two-dimensional intensity matrix are needed to completely specify the problem. The 4-level spin 3/2 system is also examined. In theory, all six relaxation rates can be independently evaluated (for a suitable system) without necessitating measurement at the low frequency Zeeman separated levels. | | | |
Reference
| Z. Naturforsch. 55a, 79—82 (2000); received September 11 1999 | | | |
Published
| 2000 | | | |
Keywords
| NQR, 14 N, Relaxation, Two-dimensional, Cross-relaxation | | | |
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| default:Reihe_A/55/ZNA-2000-55a-0079.pdf | | | | Identifier
| ZNA-2000-55a-0079 | | | | Volume
| 55 | |
| 4 | Author
| Hiroyuki Ishida | Requires cookie* | | | Title
| H NMR Study of Ionic Motions in High Temperature Solid Phases of (CH 3 NH 3 ) 2 ZnCl 4 | | | | Abstract
| The reorientation of the tetrahedral complex anion ZnCl 4 2-and the self-diffusion of the cation in (CH 3 NH3) 2 ZnCl4 were studied by 'H NMR spin-lattice relaxation time ('H T X) experiments. In the second highest-temperature phase, the temperature dependence of *H T X observed at 8.5 MHz could be explained by a magnetic dipolar-electric quadrupolar cross relaxation between 'H and chlorine nuclei, and the activation energy of the anion motion was determined to be 105 kJ mol -1 . In the highest-temperature phase, the activation energy of the self-diffusion of the cation was determined to be 58 kJ mol -1 from the temperature and frequency dependence of 'H T X . | | | |
Reference
| Z. Naturforsch. 55a, 412—114 (2000); received January 8 2000 | | | |
Published
| 2000 | | | |
Keywords
| Nuclear Magnetic Resonance, Molecular Motion, Cross Relaxation, (C^N^^ZnCfj | | | |
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| default:Reihe_A/55/ZNA-2000-55a-0412.pdf | | | | Identifier
| ZNA-2000-55a-0412 | | | | Volume
| 55 | |
| 5 | Author
| G. Sulzer, B. Itterm, E. Diehl, B. Fischer, H.-P Frank, E. Jäger, W. Seelinger, H.-J Stockmann, H. Ackermann | Requires cookie* | | | Title
| Temperature Dependence of Impurity Induced EFG's in Extremely Diluted CuB | | | | Abstract
| The temperature dependence of impurity induced EFG 's around implanted 12B ions in Cu was measured for two lattice locations using the ß-N M R method. The induced EFG at the nearest neighbouring host atoms decreases with increasing temperature for the case of 12B stopped on interstitial sites, whereas the opposite temperature behaviour was found if 12B is situated in substi tutional sites. | | | |
Reference
| Z. Naturforsch. 49a, 354 (1994); received July 23 1993 | | | |
Published
| 1994 | | | |
Keywords
| N M R, ß radiation detected, Cross relaxation, Electric field gradient, Temperature dependence o f EFG, Impurity induced EFG | | | |
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| default:Reihe_A/49/ZNA-1994-49a-0354.pdf | | | | Identifier
| ZNA-1994-49a-0354 | | | | Volume
| 49 | |
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