Overcoming Sensitivity and Selectivity Issues in Greenhouse Gases (GHG) Monitoring with the use of Laser-based Photoacoustic Spectroscopy
Tuesday, March 09, 2021: 2:30 PM - 2:50 PM
Understanding and quantifying greenhouse gas (GHG) emissions sources is important in the research of climate change. GHG emissions monitoring has applications for example, in atmospheric studies, soil research and animal husbandry. The relevant gases are typically measured offline using GC or online using optical spectroscopic methods. Methane (CH4) and nitrous oxide (N2O) are both naturally occurring inert gases with relatIvely simple molecular structure. They are both also significant greenhouse gases with global warming potentIal of about 30 (CH4) and about 300 (N2O) times higher than carbon dioxide (CO2).
Traditional photoacoustic spectroscopy using a broadband source and optical bandpass filters has suffered from selectivity issues which has compromised the reliability of the GHG emissions quantification results obtained using photoacoustic spectroscopy . However, photoacoustic laser spectroscopy  is known to be highly sensitive and selective method for monitoring trace gases.
We demonstrate single digit ppb-level limits of detection for CH4 and N2O measured using a single quantum cascade laser source and cantilever enhanced photoacoustic detection. Five orders of magnitude of linear dynamic range can be achieved with a single-point calibration. Photoacoustic spectroscopy requires no ultra-high precision alignment of optics which makes the technology easily adapted in the field measurements.
 Butterbach-Bahl K., Sander B.O., Pelster D., Díaz-Pinés E. (2016) Quantifying Greenhouse Gas Emissions from Managed and Natural Soils. In: Rosenstock T., Rufino M., Butterbach-Bahl K., Wollenberg L., Richards M. (eds) Methods for Measuring Greenhouse Gas Balances and Evaluating Mitigation Options in Smallholder Agriculture. Springer, Cham.
 Kuusela, Tom & Kauppinen, Jyrki. (2007). Photoacoustic Gas Analysis Using Interferometric Cantilever Microphone. Applied Spectroscopy Review – Appl Spectrosc Rev. 42. 443-474
Keywords: Please select up to 4 keywords ONLY:
Environmental - Air,Environmental - Soils, Hazardous Waste,Photoacoustic,Agriculture