Capillary condensation in porous alumina observed by positronium lifetime spectroscopy

The PALS method based on time distribution measurements has been used to study capillary condensation of different gases adsorbed in microporous alumina powder. The isotherms exhibit features which are associated with a shifted gas–liquid transition. The sorption and desorption processes are irreversible presenting a hysteresis effect. Suggestions on some new aspects of the capillary condensation dynamics are made.