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Improvements in dating tooth enamel by ESR
A R Skinner1, B A Blackwell, N D Chasteen
1Department of Chemistry, Williams College, Williamstown, MA 01267, USA.
Summary
Electron spin resonance (ESR) dating is reliable even with complex spectra. Spectral variations and interference peaks in hydroxyapatite do not hinder accurate dating, with signals lasting over 10 billion years.
Area of Science:
- Geochronology
- Archaeometry
- Materials Science
Background:
- Electron spin resonance (ESR) dating relies on growth curves derived from complex spectral interpretations.
- Spectral variability and interference peaks can complicate accurate dose calculations in ESR dating.
Purpose of the Study:
- To investigate the impact of spectral variability on ESR dating accuracy.
- To determine if interference peaks in hydroxyapatite signals affect dating results.
- To assess the stability of the dating signal after artificial irradiation and annealing.
Main Methods:
- Analysis of complex ESR spectra at Q-band frequency.
- Signal subtraction techniques for spectral interference.
- Artificial irradiation and annealing of sample aliquots.
- Growth curve analysis to determine accumulated dose.
Main Results:
- Spectral variability often does not impede accurate accumulated dose calculation.
- A broad interference peak in hydroxyapatite is integral to the signal and generally not problematic for dating.
- Artificially irradiated signals show a short-lived component, but annealing confirms the dating signal's stability.
- The ESR dating signal demonstrates a lifetime exceeding 10^10 years.
Conclusions:
- ESR dating is robust despite spectral complexities and interference peaks in hydroxyapatite.
- Proper annealing procedures ensure the long-term stability and reliability of the ESR dating signal.
- Previously unsuitable samples can yield accurate ESR dates with careful spectral analysis.