Quantitative high-resolution cathodoluminescence spectroscopy of smithsonite

Abstract

Five smithsonite samples from locations in Germany, Mexico and Namibia have been investigated with cathodoluminescence (CL) spectroscopy and trace-element analyses. As with other carbonates, the CL properties of smithsonite are mainly controlled by Mn 2+ -and Fe 2+ -incorporation, because these elements are the most important activator and quencher species, respectively. Additional trace elements may have either a quenching effect (Cu) or have only small or no influence (Ca, Pb). A linear correlation exists between the Mn content and the intensity of the Mn-emission band in smithsonite, which can be quantified, if the Cl intensity is related to the number of moles of Mn rather than the weight fraction. A correlation between the Cl intensity and the Mn concentration, which is valid for all trigonal carbonates, is obtained from the published results of calcite, dolomite and smithsonite. Matrix effects due to the different chemical composition of the carbonate minerals seem to be of lesser importance.

Blue cathodoluminescence related to defect center in smithsonite

“…In the heating process, the peak positions of the red emissions are slightly shifted to shorter wavelength because of an increase in metal -ligand distance, whereas the peak positions of the blue emissions are independent of the sample temperature. This fact confirms that the blue emission in smith- sonite is derived from defect centers, as previously expected (Götte and Richter, 2004).…”

“…The blue CL, however, was expected to be from lattice defects analogically based on the same effect in other carbonates. Götte and Richter (2004) indicated negligibly small influence of Fe (˂2000 ppm) and Cu (˂1500 ppm) impurities on red and blue CL emissions in smithsonite. Therefore, we selected the samples of S08 and S17 with the component of blue emission for the characterization of their defect centers.…”

“…The luminescence of blue to red, including purple, has been observed in many kinds of smithsonite (Marshall, 1988;Götte and Richter, 2004), but no other colors have been recognized. This observation suggests two emission centers related to red and blue luminescence exist in smithsonite.…”

“…This observation suggests two emission centers related to red and blue luminescence exist in smithsonite. According to Götte and Richter (2004) and Cu 2+ on red CL emission. Almost no influence of Ca and Pb was observed.…”

“…Smithsonite, in the group of trigonal carbonates, has various types of emission centers in red and blue regions, and occasionally shows bright -blue to purple luminescence. Götte and Richter (2004) clearly articulated the correlation between CL features in smithsonite and impurity elements of Mn 2+ as activator and Fe…”