CHARACTER OF F CORE EXCITONS IN ALKALI FLUORIDES STUDIED BY RESONANT AUGER-SPECTROSCOPY

The resonant KLL Auger spectra of fluorine have been measured from in situ evaporated films of LiF, NaF, and KF using synchrotron radiation of the MAX I storage ring, Lund, Sweden. The measured Auger electron s pectra show strong enhancement at the F 1s absorption edge. New Auger peaks appear at excitation energies below the photoionization threshol d. These peaks are shifted to higher kinetic energies in comparison wi th the normal Auger spectra. They correspond to the excitation of the core excitons followed by the resonant Anger transitions where the exc ited electron remains as a screening spectator electron during the Ang er decay. With the aid of resonant features we have identified the reg ions of different character inside the comparatively wide absorption p eaks. The atomic picture and the comparison with the isoelectronic Ne atom have been applied successfully in the interpretation of the spect ra of F.