An EPR investigation of Ag0 and Ag2+ in irradiated single crystal of potassium fluoride doped with silver fluoride

The electron paramagnetic resonance absorption spectra of a singly ionized diatomic fluoride molecule-ion F2-, atomic silver Ag0, and divalent silver Ag2+ contained in single crystals of potassium fluoride were re-examined at X-band wavelengths. The F2- and Ag0 centers are produced simultaneously by γ-irradiation at liquid nitrogen temperature. The divalent silver Ag2+ centers are formed by subsequently warming the irradiated samples to room temperature for a few hours and then cooling to 77 K. All field-strength positions of resonance-absorption lines observed at low temperatures were satisfactorily predicted by computer simulation. The high degree of resolution exhibited by the spectra is due in part to the large nuclear magnetic moment of fluorine and in part to the fact that spectral lines in KF are narrow compared to those of similar systems in other alkali halide crystals. For atomic silver, the hexafluoride cluster is cubic. By contrast, the divalent silver center is tetragonally distorted along a crystal cube edge as a consequence of the Jahn-Teller effect