'In situ'observation of crystallization in propylene carbonate, salol and m-toluidine

摘要

Positron annihilation lifetime measurements have been performed on three molecular systems: propylene carbonate, salol and m-toluidine at the temperature range from 20 K up to 300 K. The time dependences of the orthopositronium lifetime and intensity have been observed at the temperature range between a solid state and the liquid state. These changes can be explained as transitions from the amorphous phase to one or two crystalline phases. The crystallization process from cooled liquid was observed in all three cases at different temperatures on the time scale up to 60 hours.