Electron-Gamma PAC: New Possibilities for NQI Studies

The application of hyperfine interaction techniques to problems in solid state physics has been stead-ily growing over the last decade with the use of radioactive ion beam facilities such as ISOLDE at CERN. New applications of the e--γ Perturbed Angular Correlation (PAC) technique are underway at ISOLDE using probe nuclei with highly converted cascades. In this paper we present the motivation for extend-ing PAC experiments to elements/isotopes not usable with the conventional γ-γ PAC technique. Examples will be shown where the long-lived 73As/ 73Ge, the short lived 127Ba/ 127Cs and the 197mHg/ 197Hg decay cascades are applied to measurements of nuclear quadrupole interactions in materials.