ABSOLUTE PHOTOLUMINESCENT EFFICIENCY AND PHOTON DAMAGE OF SODIUM-SALICYLATE IN THE SOFT-X-RAY REGIME

We have measured the absolute photoluminescent efficiency of sodium salicylate from 70 to 400 eV, as well as the inelastic electron-scattering spectrum from 0 to 200 eV. We find that features in the luminescence spectrum can be described well by using a model incorporating absorptance, reflectance, carrier-diffusion length, and reduced surface-recombination velocity. We have also measured the dose (total photons/unit area) dependence of the model's efficiency at several photon energies. Results indicate a decrease in efficiency when dose and x-ray energy are increased, which makes this material a nonideal choice for long-term stable detection of high-intensity soft x rays. The decrease in efficiency is caused by a bulk-damage process that is second order in the number of electron-hole pairs produced by the incident x rays, as well as by changes in surface-recombination velocity.