Exploring sources of variation in thermoluminescence emissions and anomalous fading in alkali feldspars

RIEDESEL, S., BELL, Anthony, DULLER, G.A.T., FINCH, A.A., JAIN, M., KING, G.E., PEARCE, N.J. and ROBERTS, H.M. (2021). Exploring sources of variation in thermoluminescence emissions and anomalous fading in alkali feldspars. Radiation Measurements, 141, p. 106541.

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Alkali feldspar is routinely used in retrospective dosimetry using luminescence methods. However there is a signal loss over time, termed ‘anomalous fading’, which results in age underestimation if uncorrected. Although significant improvements have been made in recent years, luminescence dating of feldspars remains challenging. This paper investigates the relationships between chemistry, structural state and the scale of exsolution with thermoluminescence (TL) emission spectra and infrared stimulated luminescence (IRSL) fading rates. We measure TL emission spectra, where possible linking the recombination site to physical features of the feldspar crystals. We show that fading rates are lowest in ordered end-member Na- and K-feldspars but significantly greater in disordered end-members, showing that Al–Si order influences fading. As well as having very low fading rates, ordered end-member samples have distinctive TL emission spectra, with the yellow-green emission dominant, while all other samples have a dominant blue emission. Perthite, i.e. exsolved members of the (Na,K)-feldspar solid solution, show greater fading than disordered end-members and fading is greatest in semi-coherent macroperthite. We propose that the state of Al–Si-order, and the occurrence of defects and dislocations at the perthite lamellar interfaces influence anomalous fading rates in feldspar.

Item Type: Article
Additional Information: ** Article version: AM ** Embargo end date: 31-12-9999 ** From Elsevier via Jisc Publications Router ** Licence for AM version of this article: This article is under embargo with an end date yet to be finalised. **Journal IDs: issn 13504487 **History: issue date 05-02-2021; accepted 31-01-2021
Identification Number: https://doi.org/10.1016/j.radmeas.2021.106541
Page Range: p. 106541
SWORD Depositor: Colin Knott
Depositing User: Colin Knott
Date Deposited: 09 Feb 2021 17:24
Last Modified: 05 Feb 2022 01:18
URI: https://shura.shu.ac.uk/id/eprint/28122

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