X dating direct
This inherent destructive aspect of OSL/IRSL measurement requires that the luminescence readout be as efficient as possible (since the population of trapped electrons decreases over stimulation time), and that any irreversible (sensitivity) changes between the readout of the natural and the laboratory generated OSL/IRSL signals are corrected for.In contrast, an alternative trapped charge dating technique, electron-spin-resonance (ESR), can directly detect the trapped electrons in a non-destructive manner; however, the ESR dating method has had a restricted application in sediment dating because of the difficulty of optically zeroing the signal prior to burial(a) A schematic showing the mechanisms of Infra-red Photoluminescence (IRPL) and Infra-red stimulated luminescence (IRSL) generation in feldspar.
However, historically, this potential of IRSL has not been exploited because of the loss of trapped charge with time due to quantum mechanical tunnelling, a process commonly referred to as anomalous fading.
Low temperature (7–295 K) spectroscopic and time-resolved investigations suggest that IRPL is generated from excited-to-ground state relaxation within the principal (dosimetry) trap.
Since IRPL can be induced even in traps remote from recombination centers, it is likely to contain a stable (non-fading), steady-state component.
We demonstrate that this new signal is a steady state signal, i.e.
it can be measured non-destructively, and it may be used for sediment dating.), we excited it with a laser emitting at 1.40 e V (885 nm) at 295 K.