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11.
Mansfeld D Miersch L Rüffer T Schaarschmidt D Lang H Böhle T Troff RW Schalley CA Müller J Mehring M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(52):14805-14810
The reaction of [Bi(22)O(26)(OSiMe(2)tBu)(14)] (1) in THF with salicylic acid gave [Bi(22)O(24)(HSal)(14)] (2) first, which was converted into [Bi(38)O(45)(HSal)(22)(OH)(2)(DMSO)(16.5)]·DMSO·H(2)O (3·DMSO·H(2)O) after dissolution and crystallization from DMSO. Single-crystal X-ray diffraction analysis and ESI mass spectrometry associated with infrared multi-photon dissociation (IRMPD) tandem MS experiments confirm the formation of the large and quite stable bismuth oxido cluster 3. The reaction of compound 2 with the butoxycarbonyl(BOC)-protected amino acids phenylalanine and valine (BOC-PheOH and BOC-ValOH), respectively, resulted in the formation of chiral [Bi(38)O(45)(BOC-AA)(22)(OH)(2)] (AA=deprotonated amino acid), as shown by a combination of different analytical techniques such as elemental analysis, dynamic light scattering, circular dichroism spectroscopy, and ESI mass spectrometry. 相似文献
12.
205Tl-NMR in Tl2Ba2Can-1CunO8?δ for differentn and δ is reviewed. Forn=2,3 the205Tl spectra consist of two lines. The main line arises from Tl(1) in the TlO-layer whereas the defect line belongs to Tl(2) in the Ca-layers between the CuO2-layers. The temperature dependent Knight shift of the Tl(2) (defect) line is caused by the hyperfine interaction with the CuO2-layer and is strongly related to the oxygen content of the sample. We find quasipartticle behavior for the T1(2) line similar to the89Y Knight shift in the YBa2Cu3O6+δ system. In contrast the T1(1) line shows strong antiferromagnetic correlations with indication of pseudo spin gap opening above the superconducting transition temperatureT c. 相似文献
13.
H. Mehring 《Fresenius' Journal of Analytical Chemistry》1900,39(3):162-163
Ohne Zusammenfassung 相似文献
14.
The correlation time τi of the impurity electronic spin in the Kondo system Cu:Fe has been measured over the temperature range 4.2 K?T?300 K (TK=27.6 K) by means of NMR relaxation of impurity neighbour nuclei. τi being in the sub-picosecond region varies with temperatures as predicted by the model calculation of Götze and Schlottmann. 相似文献
15.
W. Höptner M. Mehring J.U. Von Schütz H.C. Wolf B.S. Morra V. Enkelmann G. Wegner 《Chemical physics》1982,73(3):253-261
The longitudinal relaxation rates of the protons and the fluorine were determined for the radical cation salt (fluoranthenyl)2+PF6? as a function of the temperature. These data are compared with the temperature dependence of the pulsed ESR signal amplitude at the same Larmor frequency (44 MHz). Whereas the fluorines are relaxed mainly by the reorientational motion of the anions and by the interaction with fixed paramagnetic impurities, the protons are relaxed additionally above 150 K predominantly by highly mobile paramagnetic species, whose concentration could be determined directly via the signal amplitudes of the NMR and ESR signals in the same set up. The Pauli susceptibility χcs = 3.1 ×10?5 cm3/mole which is derived from this experiment and the Korringa relation (T1H4?)?1 = constant of the proton relaxation leads to the assumption of a metal-like behavior of the salt above 183 K. The observation that the protons of the cation stacks, rather than the fluorines on the anions are relaxed by the mobile paramagnetic species favors the assumption of one-dimensional spin transport within the fluoranthenyl stacks, which is further supported by an ω dependence of T1H?1. 相似文献
16.
4π rotational symmetry (spinor behaviour) of a two-level subsystem, connected by a double quantum transition is demonstrated in the case of a spin-1 nucleus (deuterium). 相似文献
17.
The non-markovian behaviour of coupled nuclear spins in the spin-locking experiment is investigated both experimentally and theoretically. 相似文献
18.
Spin lattice relaxation T1 of naturally abundant 13C nuclei in squaric acid was measured close to the antiferroelectric-paraelectric phase transition temperature Tc = 373 K. A rapid increase in is observed close to Tc coming from above, which follows the power law where . This behaviour is explained on the basis of the two-dimensional character of the fluctuations. 相似文献
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