Anisotropic magnetic susceptibility

The Curie spin relaxation is also called magnetic susceptibility relaxation. Vega and Fiat (52) have also considered the Curie spin relaxation originating from anisotropic magnetic susceptibility, rather than an isotropic one as assumed in Eqs. (21-23). 

Since this dipolar interaction remains in isotropic media as similarly found for the contact shift (see sect. 2.1), it is often termed as the pseudo-contact shift. For the general case of a complex possessing an anisotropic magnetic susceptibility tensor, Kemple et al. (1988) show that the pseudo-contact shift spherical coordinates of the resonating nucleus in an arbitrary axes system with the lanthanide metal ion i (III) located at the origin (fig. 1)... 

The steps to be followed may be summarized. Secular determinants must be constructed for each of the doubly degenerate levels in both directions. First-order Zeeman coefficients must be evaluated for each direction. Matrix elements connecting the three secular determinants must be evaluated to yield second-order Zeeman coefficients. The first-and second-order Zeeman coefficients must be substituted into the Van Vleck equation to yield the anisotropic magnetic susceptibilities x and x - Generally, anisotropic magnetic properties are discussed in terms of /x and n since the variation of these anisotropic components are much more easily visuaUzed. 

Thermal extrusion of dinitrogen from the adduct of benzene with diazomethane, and from the pyrazoline adducts of fullerenes with diazoalkanes (to give 6-5-open methanofullerenes), are believed to feature a Mobius aromatic transition state with a highly anisotropic magnetic susceptibility. ... 

FIGURE 93 Temperature dependence of the anisotropic magnetic susceptibility of CeRh2Si2 at ambient pressure (Mori et al., 1999). 

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