Direct, Precise Measurements of Isotopologue Abundance Ratios in CO₂ Using Molecular Absorption Spectroscopy:...

Area of Science:

• Atmospheric Chemistry
• Spectroscopy
• Geochemistry

Background:

• Precise isotopic ratio measurements are crucial for understanding Earth's climate history.
• Traditional methods like mass spectrometry are effective but can be resource-intensive.
• Optical absorption spectroscopy offers a potential alternative for isotopic analysis.

Purpose of the Study:

• To develop and validate an ultrasensitive absorption spectrometer for precise oxygen isotope measurements in CO2.
• To demonstrate the capability of optical absorption methods for detecting 17O anomalies.
• To compare the performance of this new technique with existing isotopic ratio mass spectrometry.

Main Methods:

• Utilized a sub-kHz line width laser source with 30 Hz/s stability.
• Employed a high-stability cavity-ring-down-spectroscopy setup.
• Measured isotopic ratios δ17O and δ18O in carbon dioxide (CO2).

Main Results:

• Achieved direct and precise measurements of δ17O and δ18O in CO2.
• Demonstrated the first optical absorption measurements of 17O anomalies in CO2.
• Attained a precision better than 10 ppm, meeting paleo-environmental application requirements.

Conclusions:

• Optical absorption spectroscopy is a competitive alternative to traditional isotopic ratio mass spectrometry.
• The developed spectrometer enables high-precision analysis of oxygen isotopes in CO2.
• This technique advances the study of paleo-environmental conditions through isotopic analysis.