Positronium annihilation study of surface modified silica gel particles

The positronium annihilation of surface modified silica gel particles was discussed. The groups of advanced materials analyzed by Positronium Annihilation Lifetime Spectroscopy (PALS) were found to be an excellent media to investigate positron annihilation from intermolecular meso- and nano- pores. Positron annihilation lifetime spectroscopy (PALS) has become popular as a tool to determine nanometer-sized voids in solids. PALS makes a correlation between positronium lifetimes and void sizes which is the key feature that allows to transform a lifetime distribution into a pore-size distribution. PALS measurements probe that catalysts are an interesting frame of study for positronium annihilation in porous media because of the decomposition of the spectra into four elementary e+ and p-Ps annihilations and o-Ps annihilation in inner and outer spaces