New results were reported concerning the characteristics of the photoluminescence and radioluminescence emissions, at 865 and 910nm, which were emitted by K-rich feldspars. The infra-red luminescence of the K-rich feldspars was compared with the well-known infra-red luminescence of Pb-doped KCl and with a study of the infra-red luminescence of Pb-rich amazonite (KAlSi3O8). The emissions from both the K-rich feldspar and the KCl were attributed to electron transitions from the 72P1/2 and 72S1/2 excited states to the 62S1/2 ground state of Pb+. The Pb+ originated from the interaction processes of Pb2+ cations which replaced K+ cations in the tetrahedral feldspar framework, or the cubic lattice of KCl, under ionizing radiation (Pb2+ + β, γ, … → Pb+). This radiatively induced conversion was reversed by heat treatment of the minerals (Pb+ + T → Pb2+). Also, the Pb+ centers could be optically bleached; which was also interpreted as a reversed conversion: Pb+ + ħω → Pb2+. It was concluded that the results had important implications for the precision of a new luminescence dating method for Quaternary sediments which was based upon the infra-red radiofluorescence of K-rich feldspar grains.

Infrared Luminescence of Pb+ Centers in Potassium-Rich Feldspars. G.Erfurt: Physica Status Solidi A, 2003, 200[2], 429-38