Korringa product

The temperature independence of the Korringa product T T is a better indicator of the metallic character of an NMR signal than the value of its shift. In most metal hydrides, the spin lattice relaxation at room temperature contains important contributions from the diffusive motion of the proton in the hydride lattice. To investigate the Korringa product one must work at relatively low temperatures for the palladium hydrides only values of x > 0.65 are accessible (Fig. 20). For x = 1, 7 T = 46 sK (67), but no values have been given for the shift. Supposing that the total shift 5(1) can be derived from Eq. (21) with the parameters given previously for the palladium black, we obtain 5(1) 51 ppm. From the Ti T value... 

Fk . 22. Spin lattice relaxation rate Tl of II in bulk Pdll, with x in the 0.7 to 0.8 range as a function of temperature and for several Larmor frequencies vo The straight line indicates a temperature-independent Korringa product TiT. characteristic of metallic behavior there is a nonzero LDOS on the H at the Fermi energy, in qualitative agreement with Fig. 21b. [Reproduced with permission from Schoep el al (68). Copyright 1974 Filsevier Science.]... 

The Korringa product , defined as (vhk) plyT y KlT T, should equal unity... 

---