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Updated: Aug 12, 2026

Implementation of a Reference Interferometer for Nanodetection
Published on: April 26, 2014
13CO2/12CO2 isotopic ratio measurements using a difference frequency-based sensor operating at 4.35 micrometers
M Erdelyi1, D Richter, F K Tittel
1Rice Quantum Institute, Rice University, Houston, TX 77005, USA.
Abstract:
A portable modular gas sensor for measuring the 13C/12C isotopic ratio in CO2 with a precision of 0.8%(+/-1 sigma) was developed for volcanic gas emission studies. This sensor employed a difference frequency generation (DFG)-based spectroscopic source operating at 4.35 micrometers (approximately 2300 cm-1) in combination with a dual-chamber gas absorption cell. Direct absorption spectroscopy using this specially designed cell permitted rapid comparisons of isotopic ratios of a gas sample and a reference standard for appropriately selected CO2 absorption lines. Special attention was given to minimizing undesirable precision degrading effects, in particular temperature and pressure fluctuations.

