Korringa-like relation

Although it is required to refine the above condition I in actuality, this rather simple but impressive prediction seems to have much stimulated the experiments on the electrical-conductivity measurement and the related solid-state properties in spite of technological difficulties in purification of the CNT sample and in direct measurement of its electrical conductivity (see Chap. 10). For instance, for MWCNT, a direct conductivity measurement has proved the existence of metallic sample [7]. The electron spin resonance (ESR) (see Chap. 8) [8] and the C nuclear magnetic resonance (NMR) [9] measurements have also proved that MWCNT can show metallic property based on the Pauli susceptibility and Korringa-like relation, respectively. On the other hand, existence of semiconductive MWCNT sample has also been shown by the ESR measurement [ 10], For SWCNT, a combination of direct electrical conductivity and the ESR measurements has confirmed the metallic property of the sample employed therein [11]. More recently, bandgap values of several SWCNT... 

In 1983, Kume et al. found the Korringa-like relation const, in Brs-doped PA, characteristic of metallic systems [351]. They also found the same relation for AsF( -doped PA with an extra peak below 100 K, probably due to molecular motion of dopant ions. In both systems the Pauli-like susceptibility was observed. From analysis of the relaxation data they derived ctnmr as 4x10 S/cm for Br3 -PA and 1 X 1 O S/cm for AsFfi -PA, which are compared with cT(ic=10 and 600 S/cm, respectively [351]. These estimations should be viewed with caution, since the same ambiguity as the first example of [143] is included. 

The relaxation rate (l/Tj) of H NMR show the Korringa relation above 7).. Far below T, an enhancement of l/Tj was observed in the Cu(NCS)2 and Cu[N(CN)2]Br salts just like P (ET)2l3 but the enhancement is higher. The origin of the l/Tj enhancement is not understood yet, although vortex melting is proposed as one possible origin. C NMR measurements on Cu(NCS)2 and Cu[N(CN)2]X (X = Cl, Br) salts of ET enriched with C at the central C JC bond indicate the same tempo--ature dependence of 7 , among these three salts above 50 K. 

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