Nitrous oxide (N₂O) and carbon monoxide (CO) are important drivers in global warming. However, there are many difficulties in reliable monitoring, especially for N₂O, as the concentration of N₂O in atmospheric is only a few hundred parts per billion. However, the compatibility precision recommended by World Meteorological Organization (WMO) is much lower. Therefore, a solution that can offer more precise monitoring is needed.

Researchers led by Prof. GAO Xiaoming from the Hefei Institutes of Physical Science (HFIPS) of the Chinese Academy of Sciences developed a dual gas sensor with high precision and low drift to measure atmospheric N₂O and CO. Related findings were published in Sensors and Actuators B: Chemical.

The researchers designed an improved White Cell to obtain long optical path length (76 m) at a short base length (34.5 cm).  The radio frequency noise was equipped to low optical fringes. Combined with an Interband Cascade Laser, they got a high precision spectrometer for atmospheric greenhouse gases N₂O and CO.

With this spectrometer, the researchers can test micro-daily-drift (less than 1.5 part per trillion). The precisions of N₂O and CO reached 0.065 part per billion and 0.133 part per billion, respectively, which meets the requirement of WMO.

This work provides a potentially valuable laser spectrometer for highly precise measurement of greenhouse gases, which is of great significance to the monitoring and suppression of global warming.

Field deployment photograph and time series of N2O and CO measured concentration using the developed sensor from outdoor air during 48 h on August 14-15, 2020. (Image by SHAO Ligang) 

Schematic diagram of the developed dual gas sensor. (Image by SHAO Ligang)