Nuclear G-factor Research Articles

THE RATIO OF THE NUCLEAR g-FACTORS FOR B11 AND B10

The nuclear magnetic resonarce (N.M.R.) and atomic hyperfine structure methods for the measurement of a nuclear g-factor depend upon the interaction of the nuclear magnetic moment with an appiied external magnetic field or with an internal atomic field, respectively. In the N.M.R. method the ratio of the resonance frequencies for two isotopes gives the ratio of their nuclear g-factors directly. However for some pairs of isotopes the terms containing the effects of the internal fieids differ slightly. In such cases, the ratio of the A's, the internal interaction constants, obtained by the atomic hyperfine structure method is not exactiy equal to the ratio of the g's. It has recentiy been pointed out that, to establish the h.f.s. anomaly for boron, a more precise vdiue is needed for the ratio of the nuclear gvalues of B/sup 11/ and B/sup 10/. The values for the ratio of A's calculated from a h.f.s. measurement and the g values obtained by N.M.R. method agree within the iatter's rather large limits of error so that there appears to be no h.f.s. anomaly. (A.C.)

Nuclear magnetic relaxation and resonnance line shift in metals

A detailed theory is given of the nuclear relaxation time in metals. The 1/ T law of H e i t l e r and T e l l e r, which is imposed by the statistics of the electrons, is obtained by using the Bloch approximation of metals. An approximate relation is derived between the relaxation time τ and the relative line shift ΔH/H, viz. τ( ΔH H ) 2 = ℏ π kTg 2 where g is the nuclear g-factor in Bohr-units. The experimental results on 7Li, 27Al and 63Cu are discussed with special reference to the influence of the correlation between the electrons. The deviations from the 1/ T law for Li are all or nearly all attributed to the influence of paramagnetic impurities.