Does hole instability cause anomalous fading of luminescence in feldspar?

Optically or thermally stimulated luminescence (OSL or TL) from feldspar, the most ubiquitous mineral in the Earth's crust is widely used in dosimetry and geochronology. Despite decades of research, the mechanism of OSL and TL dose underestimation arising from anomalous fading in feldspars remains poorly understood. It is commonly assumed that anomalous fading arises from the tunnelling of electrons from the principal trap, however, this causal mechanism has never been confirmed because of the lack of methods available to directly probe the trapped electrons. The recent discovery of infrared photoluminescence (IRPL), a radiophotoluminescence (RPL) signal produced by intra-defect resonant excitation in the electron trap, allows direct testing of this assumption. The unique coupled RPL-OSL physical system available in feldspar can provide insights into the dynamics of both electron and hole traps individually and, thus, improve our understanding of electron-hole recombination in this complex material.