Relaxation and phonon bottleneck of 169Tm nuclear spins in TmPO 4 : evidence for the direct process ?

The results summarized above lead us to the follow- ing interpretation : the thermal decay of o: centers obtained by optical bleaching of F centers is due to the

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When the indirect coupling between f-electrons on differrent sites is not strong enough to yield the ordering of electronic spins, the ordering of nuclear spins takes

proton relaxation, as pointed out before. More quantitatively an upper bound can be obtained for the rate of motion of the NMP spins. electronic Larmor frequencies.

- Divers résultats nouveaux, complétant l’étude de la relaxation d’une vapeur alcaline par collisions d’échange de spins électroniques, sont donnés ici : état

« normal » nuclei, for the study of nuclear magnetic ordering «in the laboratory frame » are essentially 1) a high critical temperature and 2) a short

These measurements show that at these temperatures spin- lattice relaxation does not depend on the concentration of paramagnetic ions and it is demonstrated that at high

These data therefore suggest that the BGS mecha- nism is dominant at low fields, and that the bottle- necked relaxation time should be used in the expres- sion