Measurement of NO2 with the PhoNO photolytic converter system

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Scientists at Global Analyzer Systems Ltd. (GASL) have constructed a prototype of a novel photolytic NO2converter that can be used to upgrade existing NO/NOx chemiluminescence ambient air monitors. Theseinstruments are used by environmental monitoring agencies and emission stack monitors to quantify NO andNO2. Current versions use a non-specific hot metal catalyst to convert NO2 to NO, which is detected bychemiluminescence. GASL's goal is to develop a converter that is specific to NO2. They are seeking to developa scientific understanding of what gases and gas mixtures cause interferences in the prototype converter to helpbring it to market.Dr. Osthoff's group will quantify the conversion efficiency in the prototype of a variety of gases in gas streamsof known composition, including NO2 (desired) and potentially interfering gases such as HONO, ClNO2,PAN, N2O5, HO2NO2, and HNO3. Interference that might arise from photochemical decomposition ofcarbonyls and subsequent oxidation of NO to NO2 will be characterized. The experimental results will berationalized using photochemical box model simulations.Alternative quartz photolysis cells (e.g., with smaller inner dimensions) will be constructed and evaluated. Theultimate goal is to allow GASL to deliver a well-characterized, mature, and superior product to market.