Photoionization processes in F aggregate centres of LiF crystal

Extensive studies have been carried out on the optical conversion of F and F-aggregate colour centres produced in lithium fluoride single crystal on gamma irradiation. Using 308 nm XeCl laser it has been shown that significantly large population build-up of F super(+) sub(3) centre and reduction in the population of undesirable F sub(2) centres can be achieved in gamma irradiated crystal at room temperature due to multistep photoionization processes. These and other investigations have provided a scheme for possible laser action based on F super(+) sub(3) colour centres in LiF crystal at room temperature.