13CO2/12CO2 isotopic ratio measurements using a difference frequency-based sensor operating at 4.35 micrometers.

Area of Science:

• Geochemistry
• Analytical Chemistry
• Environmental Science

Background:

• Volcanic gas emissions are crucial for understanding Earth's carbon cycle and volcanic activity.
• Accurate measurement of carbon isotopes (¹³C/¹²C) in CO2 provides insights into gas origins and processes.
• Existing methods for isotopic analysis can be complex and not field-deployable.

Purpose of the Study:

• To develop a portable, modular gas sensor for in-situ measurement of the ¹³C/¹²C isotopic ratio in CO2.
• To achieve high precision (0.8% +/-1 sigma) for volcanic gas emission studies.
• To enable rapid comparison of isotopic ratios between gas samples and reference standards.

Main Methods:

• Utilized a difference frequency generation (DFG)-based spectroscopic source operating at 4.35 micrometers.
• Employed a dual-chamber gas absorption cell for direct absorption spectroscopy.
• Focused on minimizing temperature and pressure fluctuations to enhance precision.

Main Results:

• Developed a portable modular gas sensor capable of measuring the ¹³C/¹²C isotopic ratio in CO2.
• Achieved a precision of 0.8% (+/-1 sigma) for the isotopic ratio measurements.
• Demonstrated rapid comparisons of isotopic ratios using direct absorption spectroscopy.

Conclusions:

• The developed sensor is suitable for field deployment in volcanic gas emission studies.
• The sensor provides a precise and rapid method for analyzing CO2 isotopic ratios.
• Minimizing environmental fluctuations is critical for maintaining measurement accuracy.