4f instabilities of isolated rare earth ions in elements

It is demonstrated that the perturbed angular #betta#-ray distribution method following heavy ion reactions allows microscopic measurements of the local susceptibility and 4f spin dynamics of extremely dilute 4f ions in many simple metals over wide temperature ranges. Various microscopic investigations are presented of the single-ion-behavior in Kondo-like and intermediate valence systems, which considerably exceed the possibilities of the methods applied hitherto. The formation and dynamics of the 4f configuration of isolated light rare earth ions in elements are discussed in detail. (Auth.)