Residual doses and sensitivity change of post IR IRSL signals from potassium feldspar under different bleaching conditions

Abstract

Abstract:The residual doses and sensitivity change for potassium-rich feldspar (K-feldspar) have been studied using the post-infrared infrared stimulated luminescence (pIRIR) and multi-elevatedtemperature post-IR IRSL (MET-pIRIR) protocols. Laboratory simulated poorly-bleached and wellbleached samples were those K-feldspar grains bleached using a solar simulator for 10 minutes and 8 hours, respectively. The residual doses rise with stimulation temperature and time. The poorlybleached sample has larger residual doses than the well-bleached sample, especially at high stimulation temperatures. The high-temperature pIRIR signals contain a large amount of hard-to-bleach signals. A decrease of luminescence sensitivity was observed after conducting a high-temperaturetreatment in the measurement cycles. The sensitivity decreases significantly between the first and the second cycle. The extent of decrease in sensitivity shows a clear temperature trend. The higher the stimulation temperature of pIRIR signals is, the larger the sensitivity decreases. This decrease is more severe for the poorly-bleached sample than for the well-bleached sample, and could possibly lead to problems in sensitivity correction.

WHAT THE BRICKS TELL US FROM A TEMPLE AT BURKHAN KHALDUN MOUNTAINS: CHRONOLOGICAL INSIGHTS FROM pIRIR LUMINESCENCE

“…The decrease in pIRIR De towards higher preheat temperature was observed; this is similar to the previous IRSL 50 measurements, however, this is in contrast to the increase in pIRIR De reported for unheated feldspar, e.g. [16], which is explained in terms of the hard-to-bleach signals [17]. The results based on pIRIR 290 are considered as erroneous due to the behavior of the pIRIR 290 signals; signals stimulated at higher temperature become harder to bleach resulting in considerable residual doses; therefore the pIRIR signal at lower stimulation has been suggested for young samples [16].…”

“…On the other hand, the sensitivity of pIRIR signals in unheated samples was reported to decrease with the increase of the stimulation temperature [17]. We examined the pIRIR 180 and pIRIR 290 test dose signal intensities shown in Fig.2e; when comparing the pIRIR 290 intensities with the corresponding IR 50 intensities, the ratio increased from (pIRIR 180 / IR 50 ) to (pIRIR 290 /IR 50 ) from ~1.5 to ~5.…”

Extended-range luminescence chronologies suggest potentially complex bone accumulation histories at the Early-to-Middle Pleistocene palaeontological site of Huéscar-1 (Guadix-Baza basin, Spain)

“…In general, pIR-IR protocols involving higher measurement temperatures (preheat of 320 C/60s; stimulation at 290 C) seem to be more appropriate than those involving lower temperatures (preheat of 250 C/60s; stimulation at 225 C) when trying to isolate pIR-IR signals unaffected by anomalous fading Buylaert et al, 2011). In some cases, however, the application of more stringent pIR-IR protocols can give rise to additional complications, namely poor sensitivity correction (Roberts, 2012;Vasiliniuc et al, 2012;Chen et al, 2013), higher non-bleachable residual signals (Stevens et al, 2011;Lowick et al, 2012), and failures in basic SAR suitability tests (i.e., overestimation in doserecovery tests; Steven et al, 2011;Thiel et al, 2011a;Lowick et al, 2012;Vasiliniuc et al, 2012;Arnold et al, 2014). Such observations suggest that high temperature pIR-IR protocols may not always be applicable, and that the larger measured doses obtained by these approaches could sometimes be the outcome of systematic effects related to the more stringent measurement conditions themselves, rather than the successful isolation of a non-fading signal (e.g., Roberts, 2012).…”

Review and assessment of the potential of post-IR IRSL dating methods to circumvent the problem of anomalous fading in feldspar luminescence

“…A third possible explanation was proposed by Vasiliniuc et al (2012) and Chen et al (2013) who suggested that the D e obtained using the pIRIR(50, 290) signal is overestimated in some samples because of an unsuccessful sensitivity correction of the first measurement (i.e., the natural signal). Fading rate measurements do not involve measurement of the natural signal either in D e or dose recovery measurements, so the problem of the sensitivity correction of the natural is avoided.…”