Spectral dependence of point defect production by x rays in RbBr

F-center formation by monochromatic x rays has been studied above and below the bromine and rubidium K-absorption edges in crystals of RbBr. The x-ray beam from a double silicon crystal monochromator on 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 a wide range of monochromatic x-ray intensity, with emphasis on the nearly linear initial slope of defect formation with exposure. No significant increase in F-center formation efficiency was found upon crossing the bromine K edge, which indicates that additional Auger-cascade mechanisms do not appreciably add to the usual multiple ionization electron-hole recombination processes known to generate point defects.