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Direct, Precise Measurements of Isotopologue Abundance Ratios in CO2 Using Molecular Absorption Spectroscopy: Application to Δ17O
- Stoltmann, Tim, Casado, Mathieu, Daëron, Mathieu, Landais, Amaelle, Kassi, Samir
- Analytical chemistry 2017 v.89 no.19 pp. 10129-10132
- absorption, carbon dioxide, mass spectrometry, oxygen, paleoecology, spectrometers, stable isotopes
- We present an ultrasensitive absorption spectrometer based on a 30 Hz/s stability, sub-kHz line width laser source coupled to a high-stability cavity-ring-down-spectroscopy setup. It provides direct and precise measurements of the isotopic ratios δ¹⁷O and δ¹⁸O in CO₂. We demonstrate the first optical absorption measurements of ¹⁷O anomalies in CO₂ with a precision better than 10 ppm, matching the requirements for paleo-environmental applications. This illustrates how optical absorption methods have become a competitive alternative to state-of-the-art isotopic ratio mass spectrometry techniques.