Magnetic susceptibility probe coils

One new approach is to match the magnetic susceptibility of the materials used in probe construction to a non-zero value. Olson et al. have obtained high-resolution NMR spectra using this susceptibility matching approach. A microcoil with an active volume of 5 nL was immersed into a fluid with a magnetic susceptibility similar to that of the copper coil, and thus compensated for the susceptibility mismatch at the air/copper interface. The spectral line width achieved was under 1 Hz, and the LODs were in the 10 to lOOpmol range. 

It is obvious that for given frequency, conductivity, and magnetic permeability this behavior takes place for shorter probes with higher accuracy. Correspondingly, in order to reduce the influence of conductivity, it is appropriate to apply relatively short induction probes, in particular, single-coil arrays. However, in this case we can expect an increase of the influence of borehole radius, caverns, and eccentricity. As is well known, the relation between magnetic permeability and susceptibility in Gauss system is ... 

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