Near-Surface Generation ofFCenters by Synchrotron Radiation

Abstract

The formation of $F$ centers by monochromatic soft x-ray radiation was studied in the range of photon energies 50 to 1500 eV by use of a sensitive laser-induced luminescence technique. Production efficiencies of the order of $\frac{1 \mathrm{keV}}{\left(F \mathrm{center}\right)}$ are obtained throughout the upper end of the above energy range in KCl and KBr at 77 K. Saturation densities of about ${10}^{18}$ ${\mathrm{cm}}^{-3\mathrm{}}$ occur, with the total number of centers depending upon the depth of penetration of the radiation. Reduced efficiency is noted at the lowest energies and highest absorption coefficients, and is possibly related to the observed photodesorption of neutral and ion species from the surface.