![]() ![]() The cross-correlation between the dipolar and chemical shift anisotropy (CSA) interactions is found to be appreciable. In addition, the CH coupled spin relaxation can characterize the methyl internal rotation dynamics. Simultaneous fitting of the resulting relaxation curves with various rates and initial conditions allows for the extraction of both auto- and cross-correlated dipolar spectral densities which can provide detailed information on the molecular anisotropic reorientation. The carbon-13 multiplet spin-lattice relaxation in CH and CH spin systems is studied in detail by various nonselective and selective pulse techniques. The feasibility of NQR-NMR studies in small metal particles in the presence of strong inhomogeneous quadrupole interactions is assessed « less Measurements of relaxation rates yield T/sub 1/T = 0.03 sK, indicating a relaxation mechanism driven by the hyperfine interaction with the conduction electrons. ![]() #ELECTRIC QUADRUPOLE FIELDLINES FULL#The spectra obtained in the presence of an external magnetic field can be interpreted satisfactorily in terms more » of transitions among the eigenstates of the full Hamiltonian (Zeeman plus quadrupolar). The average quadrupole coupling frequencies measured at 5 K are, for the two isotopes. The zero-field NQR spectrum is severely broadened by a nonuniform distribution of quadrupole interactions. ![]() The nuclear-magnetic-resonance and nuclear-quadrupole-resonance (NQR-NMR) spectra of /sup 187/Re and /sup 185/Re in a powder of rhenium metal were measured in the temperature range 5-10 K both in zero field and with an external magnetic field. Therefore, the high conductivities of the crystals at high temperature may be associated with both symmetry changes in the H ( ( SO 4 ) 2 − ) 2 dimers and motion giving rise to a strong temperature dependence of T 1. This result is in accordance with the Raman processes for nuclear spin-lattice relaxation. ![]() The spin-lattice relaxation rate T 1 − 1 of the R 87 b nuclei in the two crystals was found to increase with increasing temperature, being proportional to T 7. The changes in the resonance lines of the H 1 and H 2 nuclei at T C = 400 K indicate that at this temperature, the orientations of the H ( ( SO 4 ) 2 − ) 2 dimers change in such a way that the directions of the two kinds of hydrogen bonds in these crystals become approximately the same. The superionic phase transitions described here occur at a temperature of T C = 400 K, which is about 50 K lower than the previously reported superionic transition temperature (namely, 448 K). The line shape and spin-lattice relaxation time T 1 of the H 1, H 2, and R 87 b nuclei in Rb 3 H ( SO 4 ) 2 and Rb 3 D ( SO 4 ) 2 single crystals were investigated using NMR spectrometry. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |