NUCLEAR PROBES FOR INVESTIGATING RADIATION-DAMAGE

Atomic nuclei or elementary particles, produced by particle accelerato rs or nuclear reactors, are employed as nuclear probes, or so-called o bserver atoms, which provide information about their local surrounding s on an atomic scale. The study of static and dynamic properties of de fects with these radioactive probe atoms is performed via the hyperfin e interactions. They occur between the nuclear electromagnetic moments of the probe atoms and the electromagnetic fields in their surroundin gs. From the interaction parameters the desired information on the sol id state with reference to the probe atom is obtained. For example the structural arrangement and chemical nature of the neighboring atoms, the local magnetic and electric fields, the magnetic state of the prob e atom, the binding inside the host matrix, the vibrational state and diffusion properties, and, in particular, information on the existence of intrinsic defects, i.e. self-interstitials and lattice vacanies, a nd extrinsic defects, i.e. impurity atoms at substitutional or interst itial lattice sites. Thereby, in most cases, information on defect com plexes is obtained in which the radioactive probe atom is a constiuent . The main emphasis is laid on the results of two probe techniques, Mo ssbauer effect and PAC/PAD. In addition a brief survey of other techni ques, such as beta-NMR, muon-spin rotation and blocking using radioact ive emitter atoms, is given. Microscopic details of defect centres and impurity dynamics are discussed, with attention shifting from metalli c systems and their annealing stages to defect centers in semiconducto rs.