Positron annihilation studies of materials

Positron annihilation provides sensitive and versatile probe techniques in materials science that can characterize electronic structure and vacancy-type, open volume, defects. The techniques utilize the information carried by the photons that result from the quantum relativistic process of the annihilation of a positron with its antiparticle the electron. For the implanted positron, the time to the annihilation event with a host electron depends on the electron density of the local environment probed. Annihilation normally results in the conversion to two anticolinear ? photons, this emitted radiation carries information on the momentum of the electron -positron pair at the instant of annihilation.

The present article focuses on the standard e⁺ annihilation methods applied to the study of defects in materials. Current developments in e⁺ annihilation are briefly described.