Optical studies of colour centres formed in KCl by electron-hole recombination

Experiments have been carried out to determine whether the recombination of electrons with highly oriented V k centres creates oriented H centres, in the same way as orientation is maintained during the photolysis of U 2 centres. The work has confirmed optically that H-like centres are formed by electron-V k recombination in KCl, but no polarization in the H band can be detected even when the starting V k centres are highly oriented. This implies that if H centres do separate from F centres via correlated (110) collision sequences the direction of the sequence is not maintained to its end. It has also been found that the lead impurities significantly enhance the production of H-like centres.