POINT-DEFECT PRODUCTION BY X-RAYS ABOVE AND BELOW THE BROMINE K-EDGE IN KBR

F-center formation by monochromatic X-rays has been studied above and below the bromine K-edge in single crystals of KBr at 77 K. A concentr ated beam from an undulator at the Advanced Photon Source was used to produce these point defects, which were detected by a sensitive laser- induced luminescence method. Experiments were carried out over an espe cially wide range of monochromatic X-ray intensity. Contrary to our pr evious reports, a large increase in F-center formation efficiency was not found upon crossing the bromine K-edge, which suggests that additi onal Auger-cascade mechanisms do not compete strongly with the usual m ultiple ionization electron-hole recombination processes known to gene rate point defects.