The glow peak emission due to impurities in calcite, dolomite, magnesite, aragonite, and anhydrite have been investigated by measuring and interpreting the associated spectra. The impurities considered are Mn++, Pb++, Zn++, and Sb3+.
The emission spectra due to Mn++ are interpreted on the basis of crystal field theory for transition metal ions. It is shown that the orange thermoluminescence in Mn-activated calcite, dolomite, and magnesite is due to the 4G(T1g)→6S transition in the Mn++ ion. The green thermoluminescent emission of Mn-activated anhydrite is attributed to the 4G(T2g)→6S transition in Mn++. In all cases the same transitions account for the luminescent emission also. The yellow thermoluminescence in Mn-activated aragonite is tentatively assigned to the 4G(T1g)→6S transition but there are no absorption data to verify this. The emission due to Pb++ in calcite is attributed to the 1P1→1S0 and 3P1→1S0 transitions. In Zn-activated anhydrite the emission bands are identified with transitions between the T2g and Eg levels of the ground states of ions in substitutional and interstitial positions.
Fine structure is observed in the emission bands of the Mn-activated carbonates and there is no evidence of temperature broadening. In Mn-activated anhydrite, the fine structure is missing, temperature broadening is evident, and a characteristic long-wavelength tail is observed. These effects are discussed and interpreted. An approximate configurational coordinate diagram is constructed for Mn-activated calcite and dolomite and some conclusions are drawn from the results.
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