Further investigations into the accuracy of infrared radiofluorescence (IR-RF) and its inter-comparison with infrared photoluminescence (IRPL) dating

Abstract

Infrared radiofluorescence (IR-RF) is an alternative dating technique for potassium feldspar grains, offering a higher signal stability and based on a simpler underlying mechanism than more common luminescence dating approaches. However, its accuracy when tested on known-age samples has so far shown inconsistent results. In this study, we present a refined accuracy assessment using samples that have previously produced unreliable IR-RF ages. Our approach incorporates two major methodological advancements developed over the past decade: elevated temperature measurements using the IR-RF70 protocol and sensitivity change correction by vertical sliding. To expand the dose range comparison, we included two additional samples: one expected to be in saturation and another of modern age. Additionally, we evaluated the effect of using a narrower bandpass filter to exclude any signal contributions from potentially contaminating shorter wavelength emissions. Our results following the IR-RF70 protocol with sensitivity corrections show an improvement over the original room-temperature results. For four out of the seven tested known-age samples spanning ca. 100–300 Gy (20–130 ka), we obtained results in keeping with the expected doses. Two additional modern samples, however, yielded slight dose underestimations. Introduction of a multiple-aliquot regenerative dose (MAR) protocol improved the accuracy of two out of three samples with large sensitivity changes. Finally, we also compared the new IR-RF equivalent doses (De) to those obtained with the newer dating method, infrared photoluminescence (IRPL), for the same samples, including previously published values and new measurements. Like IR-RF, IRPL is also expected to be trap-specific. We observe that, with the new improvements, the success rate of IR-RF is comparable to that of IRPL.