Positronic annihilation spectroscopy in material structure studies

A relatively new method of material structure analysis, - positronic annihilation spectroscopy (PAS) - is reviewed. The ways in which the positron annihilation process operates in metals, semiconductors and some condensed matter systems are analyzed. The scope of PAS is described and its prospects for the study of electronic and defect structure are discussed. The value of positronic spectroscopy as a tool for understanding the physics and chemistry of condensed matter is that it gives extensive and unique information on such things as the electronic structure of a material, the production of crystal lattice defects in it (in particular, by radiation damage), the evolution of the defects, and the mechanisms and kinetics of physical and chemical processes involving hydrogen atom analogues.