Color Center Formation in KI and NaCl Crystals by Pulsed Electron Beam

Abstract

It has been confirmed that F centers in KI and NaCl single crystals are produced with a time constant shorter than 20ns and 10ns, respectively, between 10K and 270 K under the pulsed electron beam from a linear accelerator. The F band due to these F centers is located at 1.87 eV and 2.75 ev in KI and NaCl, respectively which is the same position, along with its half width, as that by a conventional x-raying coloration, and the height of the band stays almost constant after 20 µs or more indicating no recombination of F and H centers. The triplet state of the self trapped exciton in KI and NaCl is not directly connected to the F center formation as well as in KCl and KBr.