Abstract.A small system for the unattended measurement of total odd nitrogen (NO y , i.e., the sum of NO and its atmospheric oxidation products) aboard civil in-service aircraft in the framework of MOZAIC is described. The instrument employs the detection of NO by its chemiluminescence with O 3 in combination with catalytic conversion of the other NO y compounds to NO at 300 • C on a gold surface in the presence of H 2 . The instrument has a sensitivity of 0.4-0.7 cps/ppt and is designed for unattended operation during 1-2 service cycles of the aircraft (400-800 flight hours). The total weight is 50 kg, including calibration system, compressed gases, mounting, and safety measures. The layout and inlet configuration are governed by requirements due to the certification for passenger aircraft. Laboratory tests are described regarding the conversion efficiency for NO 2 and HNO 3 (both >98%). Interference by non-NO y species is <1% for CH 3 CN and NH 3 , <5×10 −5 % for N 2 O (corresponding to <0.2 ppt fake NO y from ambient N 2 O) and 100% for HCN. The time response of the instrument is <1 s (90% change) for NO 2 . The response for HNO 3 is nonlinear: 20 s for 67%, 60 s for 80%, and 150 s for 90% response, respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.