Characterization of the Crystal Quality of Calcites by Electron Paramagnetic Resonance

Abstract

The linewidths B,, and anisotropies in the electron paramagnetic resonance spectra of MnZ + impurities are measured in calcite single crystals and used for the determination of the origin of line broadening. Two different mechanisms of broadening, structural and chemical, are distinguished. From the differing angular dependences of the observed linewidths, large differences in the crystal quality are inferred.The differences in quality are also apparent in the EPR spectra of powder calcites, but no information about the mechanisms can be obtained. I ) Panepistimiopolis, Zografos, GR-15784 Athens, Greece.

Biotic and inorganic control on travertine deposition at Bullicame 3 spring (Viterbo, Italy): A multidisciplinary approach

“…The actual operating frequency value was determined by using DPPH radical [2,2-di(4-tert-octyl-phenyl)-1-picrylhydrazyl, g = 2.0037] as external standard. Due to the narrow line-width of Mn(II) spectra in calcite (Vassilikou-Dova, 1993), particular care was paid to the instrumental field modulation and sweep rate. The chosen parameters were 0.5 G modulation amplitude and 100 kHz modulation frequency.…”