Nuclear acoustic resonance in europium vanadate

Abstract

The trivalent europium ion has a ground manifold 4f 6 , 7 F, in which the lowest state is J = 0, some 360 cm -1 below the first excited state J = 1. The two stable isotopes of mass 151, 153 each have nuclear spins I = 5/2. Experiments to determine the hyperfine structure are discussed in the preceding paper I; a further alternative is the use of acoustic waves. These have no direct interactions with the nuclear magnetic moments, but absorption arises through modulation of the electronic contributions to the hyperfine splittings. Nuclear electric quadrupole interactions are larger than magnetic interactions, and modulation of the electric field gradient of the lattice is expected to give a stronger effect.