On nuclear pseudoquadrupole effects in metals

A part of the apparent nuclear quadrupole coupling constants is caused by second order magnetic interactions between the nuclear magnetic moment and the electrons. In metals there is both a diagonal term and an off-diagonal term, the former being analogous to the Pauli susceptibility. Expressions are derived for the diagonal part of the pseudoquadrupole coupling constant, b pq , and numerical estimates are made in terms of the Knight shift anisotropy. In indium b pq is estimated to be about one per cent of the total quadrupole-like effect and in gallium about 4 parts in ten thousand. For the antimony isotopes 121 Sb and 123 Sb, the present estimates give a quadrupole anomaly, Δ, of -7 × 10 -5 while the experimental value is (-13 ± 3) × 10 -5 .