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ESR Dating of Optically Bleached Quartz Grains: Assessing the Impact of Different Experimental Setups on Dose Evaluations

Verónica Guilarte
Verónica Guilarte
 y 
Mathieu Duval
Mathieu Duval
   | 31 dic 2021
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Publicado en línea: 31 dic 2021
Páginas: 179 - 190
Recibido: 18 ene 2019
Aceptado: 07 oct 2019
DOI: https://doi.org/10.2478/geochr-2020-0005
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© 2019 Verónica Guilarte et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Vertical distribution of ESR signal intensities obtained for three different resonators. The ER4102ST (1) profile was obtained using an EMX micro 6/1 ESR spectrometer (setup #1), while the ER4102ST (2) and SHQE resonator profiles were derived from the Elexsys E500 ESR spectrometer (setups #2 and #3). To facilitate comparisons, ESR intensities were normalized according to the highest intensity value for each profile. Key: Distance = sample distance from the resonator centre. d = Distance from the centre to the top of the resonator.
Vertical distribution of ESR signal intensities obtained for three different resonators. The ER4102ST (1) profile was obtained using an EMX micro 6/1 ESR spectrometer (setup #1), while the ER4102ST (2) and SHQE resonator profiles were derived from the Elexsys E500 ESR spectrometer (setups #2 and #3). To facilitate comparisons, ESR intensities were normalized according to the highest intensity value for each profile. Key: Distance = sample distance from the resonator centre. d = Distance from the centre to the top of the resonator.

Fig. 2

Evolution of the ESR intensity with time using setup #2. Different temperatures were tested. Al ESR intensities were normalized to the mean ESR intensity obtained for each aliquot. Acquisition conditions: 1 scan / 5 min for the 3−5 h tests, 1 scan / 2 min for the 2 h test and 1 scan / min for the 1 h test.
Evolution of the ESR intensity with time using setup #2. Different temperatures were tested. Al ESR intensities were normalized to the mean ESR intensity obtained for each aliquot. Acquisition conditions: 1 scan / 5 min for the 3−5 h tests, 1 scan / 2 min for the 2 h test and 1 scan / min for the 1 h test.

Fig. 3

Comparison of the evolution of the ESR intensities (Al centre) with the temperature (intensities normalized for T= 117 K) for setups #1 and #2.
Comparison of the evolution of the ESR intensities (Al centre) with the temperature (intensities normalized for T= 117 K) for setups #1 and #2.

Fig. 4

ESR spectra of sample BIZ1201 (natural aliquot) for (A): Al- and (B): Ti-centres, using both, a standard ER4102ST(2) and a HSQE resonators. ESR spectra of each centre were recorded with the same acquisition parameters. For Al centre: modulation frequency = 100 KHz, modulation amplitude = 1 G, microwave power = 10 mW, sweep time = 40.96 s, receiver gain = 60 dB and T = 94 K. For Ti centre: modulation frequency = 100 KHz, modulation amplitude = 1 G, scan = 2, microwave power = 5 mW, sweep time = 61.44 s, receiver gain = 81 dB and T= 94 K. All spectra were recorded with the Elexsys E500 ESR spectrometer.
ESR spectra of sample BIZ1201 (natural aliquot) for (A): Al- and (B): Ti-centres, using both, a standard ER4102ST(2) and a HSQE resonators. ESR spectra of each centre were recorded with the same acquisition parameters. For Al centre: modulation frequency = 100 KHz, modulation amplitude = 1 G, microwave power = 10 mW, sweep time = 40.96 s, receiver gain = 60 dB and T = 94 K. For Ti centre: modulation frequency = 100 KHz, modulation amplitude = 1 G, scan = 2, microwave power = 5 mW, sweep time = 61.44 s, receiver gain = 81 dB and T= 94 K. All spectra were recorded with the Elexsys E500 ESR spectrometer.

Fig. 5

Comparison of the ESR intensities (Al centre) obtained from samples BIZ1201 and BIZ1202 with the three experimental setups. The spectra were recorded using the acquisition parameters shown in Table 3. ESR intensities were normalized according to the natural intensity of each DRC.
Comparison of the ESR intensities (Al centre) obtained from samples BIZ1201 and BIZ1202 with the three experimental setups. The spectra were recorded using the acquisition parameters shown in Table 3. ESR intensities were normalized according to the natural intensity of each DRC.

Fig. 6

Comparison of the ESR intensities (Ti centre) obtained from samples BIZ1201 and BIZ1202 with the three experimental setups. Spectra were recorded using the acquisition parameters shown in Table 3. ESR intensities were normalized according to the natural intensity of each DRC.
Comparison of the ESR intensities (Ti centre) obtained from samples BIZ1201 and BIZ1202 with the three experimental setups. Spectra were recorded using the acquisition parameters shown in Table 3. ESR intensities were normalized according to the natural intensity of each DRC.

Fig. 7

DE values (Al centre) obtained from samples BIZ1201 and BIZ1202 with the three experimental setups. DE values were obtained by the fitting of an EXP+LIN function through each DRC. Final DE values are obtained by averaging the ESR intenstities derived from the 3 repeated measurements.
DE values (Al centre) obtained from samples BIZ1201 and BIZ1202 with the three experimental setups. DE values were obtained by the fitting of an EXP+LIN function through each DRC. Final DE values are obtained by averaging the ESR intenstities derived from the 3 repeated measurements.

Fig. 8

DE values (Ti centre) obtained from samples BIZ1201 and BIZ1202 with the three experimental setups. DE values were obtained by the fitting of a Ti-2 function through each DRC. Final DE values are obtained by averaging the ESR intenstities derived from the 3 repeated measurements.
DE values (Ti centre) obtained from samples BIZ1201 and BIZ1202 with the three experimental setups. DE values were obtained by the fitting of a Ti-2 function through each DRC. Final DE values are obtained by averaging the ESR intenstities derived from the 3 repeated measurements.

Variability of the ESR intensities of samples BIZ1201, BIZ1202 (Al and Ti centres) derived from experimental setups #1, #2 and #3.

Al Centre Ti Centre
Sample Experimental setup Day Number of aliquots per sample Precision of each sample measurements: mean CV (%) Precision of 3 day measurements: mean CV (%) Precision of each sample measurements: mean CV (%) Precision of 3 day measurements: mean CV (%)
BIZ1201 Setup #1 1 13 0.82 1.67 3.80 2.59
2 13 1.05 3.63
3 13 1.04 3.62
Setup #2 1 13 0.79 2.02 2.57 4.96
2 13 1.25 3.32
3 13 1.76 3.57
Setup #3 1 13 1.31 1.28 3.82 4.15
2 13 1.58 2.66
3 13 1.54 4.08
BIZ1202 Setup #1 1 13 1.37 1.21 4.08 3.78
2 13 1.47 3.65
3 13 1.01 2.59
Setup #2 1 13 1.07 1.84 2.79 3.06
2 13 1.45 2.84
3 13 1.19 2.39
Setup #3 1 13 2.29 1.81 3.00 5.00
2 13 1.63 2.54
3 13 1.47 2.92

Description of Experimental Setups #1, #2 and #3.

Experimental Setup #1 Experimental Setup #2 Experimental Setup #3
ESR spectrometer Bruker EMX 6/1 micro Bruker Elexsys E500 Bruker Elexsys E500
Resonator model ER4102ST(1): standard cavity ER4102ST(2): standard cavity SHQE: high sensitivity cavity
Low temperature system ER4141VT Digital Temperature control system ER4131VTM Digital Temperature (stabilized via PID) ER4131VTM Digital Temperature (stabilized via PID)
Chiller Thermo Scientific NESLAB ThermoFlex 3500 (water-cooled) Riedel PC-100-02 (water-to-air cooled) Riedel PC-100-02 (water-to-air cooled)
Acquisition software Bruker Win EPR Bruker Xepr Bruker Xepr

Overview of the different groups working on ESR dating of quartz over the last decades (non-exhaustive list). The description of the experimental setup is based on the information provided in the respective publications cited in the last column.

Institution, city, country ESR spectrometer (temperature of ESR measurement) Reference
Museum National d’Histoire Naturelle, Paris, France Bruker EMX (107 K) Voinchet et al., 2010
University of Cologne, Cologne, Germany Bruker ESP 300 (115 K) Beerten et al., 2006
Centro Nacional de Investigacion sobre la Evolucion Humana (CENIEH), Burgos, Spain Bruker EMXmicro 6/1 (90 K) Duval et al., 2017a
McMaster University, Hamilton, Canada JEOL FA-100 (77 K) Burdette et al., 2013
China Earthquake Administration, Beijing, China Bruker ER041XG (77 K) Liu et al., 2010
Okayama University of Science, Okayama, Japan JEOL PX-2300 (81–84 K) Toyoda et al., 2006

Acquisition parameters employed for the three experimental setups during the ESR measurements of Al and Ti centres.

Al centre Ti centre
Experimental Setup Setup #1 Setup #2Setup #3 Setup #1 Setup #2Setup #3
ESR spectrometer EMX 6/1 micro Elexsys E500 EMX 6/1 micro Elexsys E500
Resonator model ER4102ST(1) ER4102ST(2) SHQE ER4102ST(1) ER4102ST(2) SHQE
Microwave power (mW) 10 10 5 5
Sweep width (mT) 18 18 18 18
HF modulation (kHz) 100 100 100 100
Modulation amplitude (mT) 0.1 0.1 0.1 0.1
Number of points 1024 1024 1024 1024
Conversion time (ms) 40 40 60 60
Sweep time (s) 40.96 40.96 61.44 61.44
Number of scans 1 1 2–4 2–4 ST resonator 1–2 HSQE
Receiver Gain 3169.8 60 dB 25178.5 81 dB
Temperature (K) 90 94 90 94
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