Entanglement Technologies, Inc. (ET) proposes to develop a gas analyzer for ethane and isotopologues of methane to study of methane sources and sinks, using cavity ring-down spectroscopy (CRDS). Methane is an important contributor to global climate change, and a participant in air pollutant reactions such as ozone. Understanding methane sources, sinks, and transport between them is crucial to predict its effect on climate and pollution. CRDS is an ultra-sensitive and precise optical measurement technique which is already successfully commercially deployed to monitor a wide variety of atmospheric molecules including isotopes of methane. However, these commercial analyzers lack the requisite sensitivity for NOAA research. Other methods to monitor isotopic methane (e.g. multi-pass optical absorption and mid-wave infrared spectroscopy) are difficult to reduce in size and weight for airborne deployment. CRDS can potentially achieve comparable performance with a small gas cell and air pump and short-wave (3 microns) spectrsocopy that is easier to implement than 6-8 microns. ET proposes to develop a mid-infrared CRDS analyzer using short-wave spectroscopy to measure ethane concentration to a precision of 10 parts per trillion by volume (pptv), and isotopes of methane with precisions of 0.5%0 for 13CH4/12CH4 and 10%0 for 12CH3D/12CH4, at 1 Hz measurement rate.
