Critical parameters of positron and positronium annihilation in grainy and porous solids: Ionic crystals and zeolites

Positron annihilation spectroscopy (PAS) established itself as a routine method for structural studies of ordered substances in general, but some media present PAS results that are still puzzling. This situation is notably true for solid porous systems. This work recalls reasons for possible large discordances in the PAS results on such substances but focuses attention not only on the sample production, preparation and treatment prior and during the PAS measurements but also on the determination of the appropriate measuring conditions and establishing the optimal range of interest of considerations for obtaining descriptive parameters which provide the requested critical sensitivity. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)