Abstract
Positron annihilation (PA) has been documented as a powerful tool for evaluating molecular-level open spaces in various materials such as semiconductors, gas sensors and separation membranes. There are several advantages of PA over other methods; it is nondestructive, sensitive to holes/pores (of 0.3 nm～50 nm in size) irrespective of either open or buried, while adsorption porosimetry can only detect open porosity. Furthermore, PA with a variableenergy beam is widely utilized in the investigation of thin films with thicknesses from tens nm up to several µ m. This paper demonstrates several examples of PA applications to the hole/pore characterization for functional polymer materials including separation membranes, followed by the short review of the principle and instrumentation for the PA techniques.
