Abstract
Abstract. We report on applications of the ultraviolet-light-emitting-diode-based incoherent broadband cavity-enhanced absorption spectroscopy (UV-LED-IBBCEAS) technique for optical monitoring of HONO, NO2 and CH2O in a simulation chamber. Performance intercomparison of UV-LED-IBBCEAS with a wet chemistry-based NitroMAC sensor and a Fourier transform infrared (FTIR) spectrometer has been carried out on real-time simultaneous measurement of HONO, NO2 and CH2O concentrations during the reaction of NO2 with H2O vapour in CESAM (French acronym for Experimental Multiphasic Atmospheric Simulation Chamber). The 1σ (signal-to-noise ratio (SNR) = 1) detection limits of 112 pptv for NO2, 56 pptv for HONO and 41 ppbv for CH2O over 120 s were found for the UV-LED-IBBCEAS measurement. On the contrary to many set-ups where cavities are installed outside the simulation chamber, we describe here an original in situ permanent installation. The intercomparison results demonstrate that IBBCEAS is a very well suitable technique for in situ simultaneous measurements of multiple chemically reactive species with high sensitivity and high precision even if the absorption bands of these species are overlapped. It offers excellent capacity for non-invasive optical monitoring of chemical reactions without any perturbation. For the application to simulation chambers, it has the advantage to provide a spatially integrated measurement across the reactor and hence to avoid point-sampling-related artefacts.
Highlights
Atmospheric nitrous acid (HONO) is known as a major source of hydroxyl radicals (OH) (Harris et al, 1982; Finlayson-Pitts and Pitts, 2000) in the atmosphere through its photolysisHONO + hν(
We report on the development of an ultraviolet light-emitting diode (UV-LED)-based UVIBBCEAS instrument for simultaneous measurement of concentration ranges of HONO (0–30 ppbv), NO2 (0–120 ppbv) and CH2O (0–150 ppbv) during the processes of HONO generation through NO2 reaction with H2O in a simulation chamber
Intercomparison measurements of HONO, NO2 and HCHO between incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS), NitroMAC and Fourier transform infrared (FTIR) have been performed during the reaction of NO2 with H2O vapour in the CESAM atmosphere simulation chamber
Summary
Atmospheric nitrous acid (HONO) is known as a major source of hydroxyl radicals (OH) (Harris et al, 1982; Finlayson-Pitts and Pitts, 2000) in the atmosphere through its photolysis. Laboratory studies show that H2O vapour and surface-adsorbed H2O both play an important role in the conversion process from NO2 to HONO (Finlayson-Pitts and Pitts, 2000; Spataro and Ianniello, 2014), the investigations regarding the influence of H2O on the NO2 and HONO chemistry in the real atmosphere remain a highly discussed topic (Stutz et al, 2004; Michoud et al, 2014), and a wellaccepted parameterization is still to come. HONO is sampled on aqueous/humid surfaces and converted into a species suitable to be analysed with conventional chemical analytical techniques such as ion chromatography (IC), fluorescence (FL), chemiluminescence (CL), long-path absorption photometer (LOPAP) or high-performance liquid chromatography (HPLC) (Chen et al, 2013) These wet-chemistry-based instruments often suffer from unquantified chemical interferences and sampling artefacts (Stutz et al, 2010). Agreement of uncertainties
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
