The temperature dependence of luminescence in some feldspars (80-300 K)

The temperature dependence of luminescence recombination in samples of alkali feldspar and plagioclase samples has been measured directly using x-ray stimulation in the temperature range 80-300 K. Thermal quenching between 80 and 200 K has been observed in the UV-visible emissions from selected feldspar samples and the gain has been quantified. Thermal activation energies of the quenching mechanism have been evaluated and are of the order 0.06 eV in potassium feldspars and 0.04 eV in plagioclase samples. The similarities in quenching behaviour with both potassium feldspars and plagioclases in UV-visible emissions, together with the observations of quenching in other silicate materials and the evidence from Raman and FTIR spectroscopy studies, indicate similar quenching mechanisms connected with lattice vibrations. By comparison with the Raman and FTIR studies, suggestions are made for the specific lattice motions responsible for the observed quenching.