Surface characterization of catalytic materials by positron annihilation radiation lineshapes measurements

摘要

Positron annihilation radiation lineshapes from two- dimensional angular correlation and Doppler broadened spectrum measurements are used to monitor specific surface acidity (proton concentration per unit surface area) of catalytic materials with large internal surface areas. Annihilation gamma lineshape parameter increases with internal surface area and decreases with specific surface acidity as a result of oxidation of positronium atoms at the surface by protons. These results point to a new and effective method for specific surface acidity valuations.