The dependence of orange–red IRSL decay curves of potassium feldspars on sample temperature

Abstract

This paper presents the effects of stimulation temperature on the infrared stimulated orange–red (600– 650 nm ) luminescence emission (orange–red infrared simulated luminescence (IRSL)) in potassium feldspar. Investigations explore the relationship between initial (0– 2 s ), integral (0– 100 s ), net initial (0– 2 s less background over 2 s ), net integral (0– 100 s less background over 100 s ) and last 2 s of the orange–red IRSL signals obtained for 100 s versus stimulation temperature (20–460°C) on both unpreheated and preheated samples. In the potassium feldspar sample examined, competition effects, including thermal enhancement, depletion and possibly quenching affect the orange–red IRSL signals measured. Observed effects (e.g., thermal enhancement, thermal activation energy and the decay rate) over the temperature range 20–120°C may be explained by tunnelling luminescence processes, IR transitions to the conduction band following excitations from ground state of electron trap by acquiring thermal energy from the lattice and or the random-walk band-tail model. Preheating prior to orange–red IRSL and Thermoluminescence (TL) measurements provides evidence that there are both shallow and deep traps responsible for low- and high-temperature orange–red IRSL and TL peaks. The effects of both preheating and IR bleaching on the orange–red thermally stimulated luminescence (red emission during thermoluminescence, RTL) provide evidence that bleached RTL traps have no significant contribution in the production of orange–red IRSL signals.