CHARACTERIZATION OF THE CRYSTAL QUALITY OF CALCITES BY ELECTRON-PARAMAGNETIC-RESONANCE

The linewidths B(pp) and anisotropies in the electron paramagnetic res onance spectra of Mn2+ impurities are measured in calcite single cryst als and used for the determination of the origin of line broadening. T wo different mechanisms of broadening, structural and chemical, are di stinguished. From the differing angular dependences of the observed li newidths, large differences in the crystal quality are inferred. The d ifferences in quality are also apparent in the EPR spectra of powder c alcites, but no information about the mechanisms can be obtained.