Field-dependent nuclear relaxation of spins 1/2 induced by dipole–dipole couplings to quadrupole spins: LaF3 crystals as an example
| Autor: | Danuta Kruk, O. Lips |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Nuclear and High Energy Physics
Condensed matter physics Spins Chemistry Nuclear Theory Relaxation (NMR) Biophysics nuclear relaxation ion dynamics dipolar spins solid state Condensed Matter Physics Biochemistry Spin quantum number Magnetic field Dipole Residual dipolar coupling Quadrupole Condensed Matter::Strongly Correlated Electrons Physics::Atomic Physics quadrupole spins Spin (physics) |
| Zdroj: | Journal of Magnetic Resonance. 179:250-262 |
| ISSN: | 1090-7807 |
| DOI: | 10.1016/j.jmr.2005.12.009 |
| Popis: | A general theory of spin-lattice nuclear relaxation of spins I=1/2 caused by dipole-dipole couplings to quadrupole spins S1, characterized by a non-zero averaged (static) quadrupole coupling, is presented. In multispin systems containing quadrupolar and dipolar nuclei, transitions of spins 1/2 leading to their relaxation are associated through dipole-dipole couplings with certain transitions of quadrupole spins. The averaged quadrupole coupling attributes to the energy level structure of the quadrupole spin and influences in this manner relaxation processes of the spin 1/2. Typically, quadrupole spins exhibit also a complex multiexponential relaxation sensed by the dipolar spin as an additional modulation of the mutual dipole-dipole coupling. The proposed model includes both effects and is valid for an arbitrary magnetic field and an arbitrary quadrupole spin quantum number. The theory is applied to interpret fluorine relaxation profiles in LaF3 ionic crystals. The obtained results are compared with predictions of the 'classical' Solomon relaxation theory. |
| Databáze: | OpenAIRE |
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