Freezing of molecular rotation in a paramagnetic crystal studied by 31P NMR


Freezing of molecular rotation in a paramagnetic crystal studied by 31P NMR

Opherden, D.; Bärtl, F.; Yamamoto, S.; Zhang, Z. T.; Luther, S.; Molatta, S.; Wosnitza, J.; Baenitz, M.; Heinmaa, I.; Stern, R.; Landee, C. P.; Kühne, H.

We present a detailed 31P nuclear magnetic resonance (NMR) study of the molecular rotation in the compound Cu(pz)2(2-HOpy) theory quantifies the related activation energies as Ea/kB = 250 and 1400 K. Further, the anisotropy of the second spectral moment of the 31P absorption line was calculated for the rigid lattice, as well as in the presence of several sets of PF6 reorientation modes, and is in excellent agreement with the experimental data. Whereas the anisotropy of the frequency shift and enhancement of nuclear spinrelaxation rates is driven by the molecular rotation with respect to the dipole fields stemming from the Cu ions, the second spectral moment is determined by the intramolecular interaction of nuclear 19F and 31P moments in the presence of the distinct rotation modes.

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Publ.-Id: 32143