Luminescence of the self-trapped exciton in KCl

AbstractRecent data on the luminescence of the self-trapped exciton in KCl are analysed, and a theoretical description is given of the temperature-dependence of the intensity, polarisation and lifetime of the emission. We conclude that emission is seen from both the lowest triplet ψT and the corresponding singlet ψT, and that recombination from both these states can occur radiatively or non-radiatively. In the processes in which an electron is captured by a VK centre and decays to these lowest singlet and triplet states we conclude (i) that when capture is initially into a triplet state the lowest state ψT is reached in almost all cases, (ii) that ψS is only populated via ψT, i.e. that when initial capture is into a singlet state recombination is almost certain to occur before ψS is reached, and (iii) during the decay processes following capture, some reorientation of the self-trapped hole can occur