Positronium formation in room temperature ionic liquids

Hirade, Tetsuya  

Positron lifetime measurements and age-momentum correlation measurements were performed for several ionic liquids to investigate free electrons through positronium (Ps, a bond state of an electron and a positron) formation. An injected positron forms spurs (cations and excess electrons) and thermalizes at the terminal spur where the positron has a chance to form Ps with one of excess electrons. When positrons and/or electrons are localized somewhere, their mobility becomes much smaller and Ps cannot be formed usually. It means that Ps formation can give information of reactions of mobile electrons and positrons. If the dry electrons can diffuse for long time, Ps formation is quite possible even at the later positron age such as 10100 ps. The slow Ps formation was observed in the room temperature ionic liquids.