Bleaching studies on Al-hole ([AlO4/h]0) electron spin resonance (ESR) signal in sedimentary quartz

A. Timar-Gabor*, A. Chruścińska, K. Benzid, K.E. Fitzsimmons, R. Begy, Mark Bailey

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

24 Downloads (Pure)

Abstract

Electron spin resonance (ESR) dating of sediments using quartz is most commonly used for older sediments (>100 ka), since large residuals render the ESR signal unsuitable for dating young sediments. The multiple-centre approach (utilising both Ti and [AlO4/h]0 signals) is usually used to test the resetting of the signals used for ESR dating. Here we work towards a better understanding of, and correction for, the residual signal in ESR samples of sedimentary quartz. We undertook multiple-centre ESR measurements using quartz [AlO4/h]0 and Ti signals on young aeolian samples of different grain sizes which have been independently dated using optically stimulated luminescence (OSL). Our results demonstrate that [AlO4/h]0 signal yields residuals indicating equivalent doses of about 500 Gy, substantially older than expected for the known OSL equivalent doses in the range of 8–37 Gy. The decay of [AlO4/h]0 signal as function of bleaching time can be represented by an exponential function. We investigate the dependence of the residual magnitude of the ESR signal as a function of the previous given dose and observe an exponential increase in the residual signal with dose. Such observations are consistent with the results of luminescence process modelling conducted for a model comprising two luminescence centres and several traps, one of which is a so-called deep disconnected trap that cannot be emptied during optical stimulation. We propose that bleaching occurs through an electron-hole recombination process with electrons released from optically sensitive traps. In addition to our new insights into the bleaching mechanisms of the [AlO4/h]0 ESR signal, we discuss the implications for the procedures used for performing residual dose corrections in ESR dating. We recommend that modern analogues be used in addition to laboratory-bleached samples when performing residual dose corrections.
Original languageEnglish
Article number106221
JournalRadiation Measurements
Volume130
Number of pages8
ISSN1350-4487
DOIs
Publication statusPublished - 2020

Keywords

  • Sedimentary quartz
  • ESR dating
  • [AlO4/h]0
  • Residual
  • Bleaching
  • Modelling

Cite this

Timar-Gabor, A. ; Chruścińska, A. ; Benzid, K. ; Fitzsimmons, K.E. ; Begy, R. ; Bailey, Mark. / Bleaching studies on Al-hole ([AlO4/h]0) electron spin resonance (ESR) signal in sedimentary quartz. In: Radiation Measurements. 2020 ; Vol. 130.
@article{208f7d400eef453c9e239798daa540dc,
title = "Bleaching studies on Al-hole ([AlO4/h]0) electron spin resonance (ESR) signal in sedimentary quartz",
abstract = "Electron spin resonance (ESR) dating of sediments using quartz is most commonly used for older sediments (>100 ka), since large residuals render the ESR signal unsuitable for dating young sediments. The multiple-centre approach (utilising both Ti and [AlO4/h]0 signals) is usually used to test the resetting of the signals used for ESR dating. Here we work towards a better understanding of, and correction for, the residual signal in ESR samples of sedimentary quartz. We undertook multiple-centre ESR measurements using quartz [AlO4/h]0 and Ti signals on young aeolian samples of different grain sizes which have been independently dated using optically stimulated luminescence (OSL). Our results demonstrate that [AlO4/h]0 signal yields residuals indicating equivalent doses of about 500 Gy, substantially older than expected for the known OSL equivalent doses in the range of 8–37 Gy. The decay of [AlO4/h]0 signal as function of bleaching time can be represented by an exponential function. We investigate the dependence of the residual magnitude of the ESR signal as a function of the previous given dose and observe an exponential increase in the residual signal with dose. Such observations are consistent with the results of luminescence process modelling conducted for a model comprising two luminescence centres and several traps, one of which is a so-called deep disconnected trap that cannot be emptied during optical stimulation. We propose that bleaching occurs through an electron-hole recombination process with electrons released from optically sensitive traps. In addition to our new insights into the bleaching mechanisms of the [AlO4/h]0 ESR signal, we discuss the implications for the procedures used for performing residual dose corrections in ESR dating. We recommend that modern analogues be used in addition to laboratory-bleached samples when performing residual dose corrections.",
keywords = "Sedimentary quartz, ESR dating, [AlO4/h]0, Residual, Bleaching, Modelling",
author = "A. Timar-Gabor and A. Chruścińska and K. Benzid and K.E. Fitzsimmons and R. Begy and Mark Bailey",
year = "2020",
doi = "10.1016/j.radmeas.2019.106221",
language = "English",
volume = "130",
journal = "Radiation Measurements",
issn = "1350-4487",
publisher = "Pergamon Press",

}

Bleaching studies on Al-hole ([AlO4/h]0) electron spin resonance (ESR) signal in sedimentary quartz. / Timar-Gabor, A.; Chruścińska, A.; Benzid, K.; Fitzsimmons, K.E.; Begy, R.; Bailey, Mark.

In: Radiation Measurements, Vol. 130, 106221, 2020.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Bleaching studies on Al-hole ([AlO4/h]0) electron spin resonance (ESR) signal in sedimentary quartz

AU - Timar-Gabor, A.

AU - Chruścińska, A.

AU - Benzid, K.

AU - Fitzsimmons, K.E.

AU - Begy, R.

AU - Bailey, Mark

PY - 2020

Y1 - 2020

N2 - Electron spin resonance (ESR) dating of sediments using quartz is most commonly used for older sediments (>100 ka), since large residuals render the ESR signal unsuitable for dating young sediments. The multiple-centre approach (utilising both Ti and [AlO4/h]0 signals) is usually used to test the resetting of the signals used for ESR dating. Here we work towards a better understanding of, and correction for, the residual signal in ESR samples of sedimentary quartz. We undertook multiple-centre ESR measurements using quartz [AlO4/h]0 and Ti signals on young aeolian samples of different grain sizes which have been independently dated using optically stimulated luminescence (OSL). Our results demonstrate that [AlO4/h]0 signal yields residuals indicating equivalent doses of about 500 Gy, substantially older than expected for the known OSL equivalent doses in the range of 8–37 Gy. The decay of [AlO4/h]0 signal as function of bleaching time can be represented by an exponential function. We investigate the dependence of the residual magnitude of the ESR signal as a function of the previous given dose and observe an exponential increase in the residual signal with dose. Such observations are consistent with the results of luminescence process modelling conducted for a model comprising two luminescence centres and several traps, one of which is a so-called deep disconnected trap that cannot be emptied during optical stimulation. We propose that bleaching occurs through an electron-hole recombination process with electrons released from optically sensitive traps. In addition to our new insights into the bleaching mechanisms of the [AlO4/h]0 ESR signal, we discuss the implications for the procedures used for performing residual dose corrections in ESR dating. We recommend that modern analogues be used in addition to laboratory-bleached samples when performing residual dose corrections.

AB - Electron spin resonance (ESR) dating of sediments using quartz is most commonly used for older sediments (>100 ka), since large residuals render the ESR signal unsuitable for dating young sediments. The multiple-centre approach (utilising both Ti and [AlO4/h]0 signals) is usually used to test the resetting of the signals used for ESR dating. Here we work towards a better understanding of, and correction for, the residual signal in ESR samples of sedimentary quartz. We undertook multiple-centre ESR measurements using quartz [AlO4/h]0 and Ti signals on young aeolian samples of different grain sizes which have been independently dated using optically stimulated luminescence (OSL). Our results demonstrate that [AlO4/h]0 signal yields residuals indicating equivalent doses of about 500 Gy, substantially older than expected for the known OSL equivalent doses in the range of 8–37 Gy. The decay of [AlO4/h]0 signal as function of bleaching time can be represented by an exponential function. We investigate the dependence of the residual magnitude of the ESR signal as a function of the previous given dose and observe an exponential increase in the residual signal with dose. Such observations are consistent with the results of luminescence process modelling conducted for a model comprising two luminescence centres and several traps, one of which is a so-called deep disconnected trap that cannot be emptied during optical stimulation. We propose that bleaching occurs through an electron-hole recombination process with electrons released from optically sensitive traps. In addition to our new insights into the bleaching mechanisms of the [AlO4/h]0 ESR signal, we discuss the implications for the procedures used for performing residual dose corrections in ESR dating. We recommend that modern analogues be used in addition to laboratory-bleached samples when performing residual dose corrections.

KW - Sedimentary quartz

KW - ESR dating

KW - [AlO4/h]0

KW - Residual

KW - Bleaching

KW - Modelling

U2 - 10.1016/j.radmeas.2019.106221

DO - 10.1016/j.radmeas.2019.106221

M3 - Journal article

VL - 130

JO - Radiation Measurements

JF - Radiation Measurements

SN - 1350-4487

M1 - 106221

ER -