Universität zu Köln

Riedesel, S., Kumar, R., Duller, G. A. T., Roberts, H. M., Bell, A. M. T. and Jain, M. (2021). Site-selective characterisation of electron trapping centres in relation to chemistry, structural state and mineral phases present in single crystal alkali feldspars. J. Phys. D-Appl. Phys., 54 (38). BRISTOL: IOP PUBLISHING LTD. ISSN 1361-6463

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Abstract

Feldspars are ubiquitous natural dosimeters widely used in luminescence dating. Despite decades of research, the lattice defects as well as the mechanisms involved in luminescence production in feldspars remain poorly understood. The recently developed method of infrared photoluminescence (IRPL) excitation-emission spectroscopy has revealed the presence of two electron trapping centres emitting IRPL at 1.3 eV and 1.41 eV (IRPL1.3 and IRPL1.41 centres), and it enables detailed investigations into the ground and excited state energies of these centres. Here we make measurements of a range of single crystal alkali feldspars to understand the effects of feldspar chemical composition, crystal structure and framework disorder on the physical characteristics of IRPL1.3 and IRPL1.41 electron trapping centres. Measurements of our sample suite reveals IRPL and IR-radioluminescence (RL) emissions at 1.41 eV, 1.3 eV and, for the first time, at 1.2 eV. Our results show that whilst the IRPL1.3 trapping centre is unaffected by the M site cation occupancy, the presence of IRPL1.41 trapping centres seems to be linked to the presence of K+ ions on M sites. However, no clear trends in IRPL and IR-RL emission energies and signal intensities with chemical composition of the samples were found. Exploring the effect of framework disorder on IRPL1.3 and IRPL1.41 emissions revealed no significant changes to IRPL and IR-RL emission energies or ground state energies of the trapping centres, suggesting that the corresponding defects are not located on bridging O ions. Variations in ground state energies across the whole sample suite range from 2.04 eV to 2.20 eV for the IRPL1.3 centre and from 2.16 eV to 2.46 eV for the IRPL1.41 centre. Variations in trap depth seem to be driven by other factors than sample chemistry, degree of Al3+ disorder and number of phases present in a single crystal feldspar. Interestingly, the IR resonance peak is invariant between samples. Regarding the use of IRPL in luminescence dating, we show that optical resetting differs for the three different emissions, with the emission at similar to 1.41 eV not being reset in some samples even after 18 h of solar bleaching.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Riedesel, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kumar, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Duller, G. A. T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Roberts, H. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bell, A. M. T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Jain, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-590317
DOI:	10.1088/1361-6463/ac10d7
Journal or Publication Title:	J. Phys. D-Appl. Phys.
Volume:	54
Number:	38
Date:	2021
Publisher:	IOP PUBLISHING LTD
Place of Publication:	BRISTOL
ISSN:	1361-6463
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language BAND-TAIL STATES; INFRARED-PHOTOLUMINESCENCE; STIMULATED LUMINESCENCE; THERMO-LUMINESCENCE; POTASSIUM FELDSPARS; RADIATION DEFECTS; EXCITATION; RADIOLUMINESCENCE; SPECTROSCOPY; ENERGIES Multiple languages Physics, Applied Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/59031