An Overview of 166Er, 169Tm and 170Yb Moessbauer Spectroscopy

The hyperfine splittings of the nuclear energy levels in rare-earth (R) isotopes are sensitive measures of the complex interplay between magnetic exchange and electrostatic crystal-field interactions operating at the atomic level. Moessbauer spectroscopy has been used to great effect in the on-going investigation of these fundamental interactions in R compounds and in this paper we present an overview of 166Er, 169Tm and 170Yb Moessbauer spectroscopy. In particular, we derive expressions for the nuclear energy level splittings incorporating both magnetic and electric quadrupole interactions, using second-order perturbation theory. Such expressions provide a useful means of fitting experimental spectra and also yield criteria for determining whether or not a proposed set of energy level values is physical or not. We also present a number of useful rules of thumb for the analysis of 166Er, 169Tm and 170Yb Moessbauer spectra and, as such, this paper is in effect a Resource Letter.