On the potential of Raman-spectroscopy-based carbonate mass spectrometry

Nicholas P. McKay, David L. Dettman, Robert T. Downs, Jonathan T. Overpeck

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The potential for using Raman spectroscopy to measure stable oxygen isotope ratios (18O/16O) in carbonates is evaluated by measuring the Raman spectra and isotope ratios of a suite of 60 synthesized, 18O-enriched calcite crystals ranging in composition from natural abundance (0.2 mole-% 18O) to 1.2 mole-% 18O. We determined the Raman-inferred isotopic ratios (RRaman) by fitting curves to the ν1 symmetric stretching peak at 1086 cm-1 and the smaller satellite peak, associated with the ν1 stretching mode of singly substituted carbonate groups (C16O2 18O) at 1065 cm-1. The ratio of the two peak areas shows a 1:1 correspondence with the 18O/16O ratios derived from standard mass spectrometry methods, confirming that the relative intensities of the ν1 symmetric stretching peaks is a direct measure of the isotopic ratio in the carbonates. The 1-sigma uncertainties of the R Raman values of the individual crystals were 0.00079 (384‰ PDB) and 0.00043 (210‰ PDB) for the four-crystal sample means. This level of uncertainty is much too high to provide significant estimates of natural variability; however, there are multiple prospects for improving the accuracy and precision of the technique. Carbon isotope ratios in carbonates cannot be measured by our approach, but our results highlight the potential of Raman-based isotope ratio measurement for C and other elements in minerals and organic compounds.

Original languageEnglish (US)
Pages (from-to)469-474
Number of pages6
JournalJournal of Raman Spectroscopy
Volume44
Issue number3
DOIs
StatePublished - Mar 2013

Keywords

  • calcite
  • carbonates
  • isotopes
  • mass spectrometry
  • oxygen

ASJC Scopus subject areas

  • General Materials Science
  • Spectroscopy

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