Isolating a violet stimulated luminescence (VSL) signal in quartz suitable for dating: Investigating different thermal treatments and signal integration limits.

The behavior of the post-blue violet stimulated luminescence (VSL) signal from quartz with respect to thermal treatments is explored. The results suggest that more than one source trap may be responsible for the VSL signal and therefore, the separation of this signal from the preceding blue stimulated luminescence (BSL) signal is challenging. Furthermore, the behavior of the VSL dose response curve (DRC) in a single aliquot regenerative (SAR) protocol is demonstrated to be influenced significantly by the test dose size and the efficacy of signal depletion prior to measurement of the test dose signal, and hence a modified VSL SAR measurement protocol is considered for further investigations in this study. The ability of this protocol to recover a given dose is tested and it is shown that by selecting different integration limits, two signals with distinct dose response characteristics can be separated from the same original VSL decay curve. Dose response curves derived from early signal integration (Signal A) saturate at ∼150 Gy and cannot recover given doses beyond this limit, whereas later signal integration (Signal B) results in a DRC that continues to grow exponentially to doses >> 500 Gy, and can recover given doses up to at least ∼3200 Gy. However, Signal B underestimates by ∼90% the equivalent dose (D e) for a sample with expected D e value of ∼500 Gy. This may suggest thermal instability of Signal B over geological time and needs further investigation. • Test dose size and prior VSL signal depletion influence dose response curves. • Two signals with different dose response characteristics can be isolated. • Dose response curves from early signal integration (Signal A) saturate at low doses (∼150 Gy). • Dose response curves from late signal integration (Signal B) grow to high doses (>> 500 Gy). • D e underestimation suggests Signal B is unstable over geologic time. [ABSTRACT FROM AUTHOR]