Isotope Ratio Dual-Comb Spectrometer

TL;DR

This paper demonstrates a dual-comb spectrometer capable of precise isotope ratio measurements, extending spectral range to mid-infrared, with repeatability comparable to traditional mass spectrometry, and potential for multi-species analysis.

Contribution

The work introduces a dual-comb spectrometer for isotope ratios, extending spectral range via difference frequency generation, and shows its capability to measure $ ext{δ}^{13}$C with high repeatability.

Findings

Repeatability with standard deviation below 2‰ over several days.

Compatible results with isotope ratio mass spectrometry.

Potential to measure multiple chemical species without major modifications.

Abstract

We demonstrate the use of dual-comb spectroscopy for isotope ratio measurements. We show that the analysis spectral range of a free-running near-infrared dual-comb spectrometer can be extended to the mid-infrared by difference frequency generation to target specific spectral regions suitable for such measurements, and especially the relative isotopic ratio $\delta {}^{13}$C. The measurements performed present a very good repeatability over several days with a standard deviation below 2$\unicode{x2030}$ for a recording time of a few tens of seconds, and the results are compatible with measurements obtained using an isotope ratio mass spectrometer. Our setup also shows the possibility to target several chemical species without any major modification, which can be used to measure other isotopic ratios. Further improvements could decrease the uncertainties of the measurements, and the spectrometer could thus compete with isotope ratio spectrometers currently available on the market.