Advancing optical isotope ratio spectroscopy for carbon dioxide

Carbon dioxide and methane levels in atmosphere have become higher than ever before. It is therefore of utmost importance to reduce emission of these greenhouse gases. In order to help this action, one has to be able to distinguish between anthropogenic and naturalemission sources. Stable isotopes of carbon dioxide can be used in this task since different sources can have unique isotopic fingerprint in their emissions [1]. Optical spectrometers are relatively low-cost and can be used in field measurements to provide near real-time data on isotopic composition of CO2. In our work, we have developed optical isotope ratio spectrometer (OIRS) to meet the strict requirements of global greenhouse gas monitoring communities.
OIRS-instrument is based on laser absorption spectroscopy (LAS) and quality of the laser will have big influence on the precision of the instrument itself. In order to improve the precision, we have tested low-noise current drivers for the laser in the analyzer. In our conference contribution, we present results from these experiments. In addition, we have tested and characterized different multipass cells, which is one of the crucial part in LASmethod and in OIRS-instrument. We will also discuss performance of these cells and our OIRS-instrument in our contribution.