Simultaneous monitoring of temporal profiles of NO3, NO2 and O3 by incoherent broadband cavity enhanced absorption spectroscopy for atmospheric applications

Abstract

An Incoherent Broadband Cavity Enhanced Absorption Spectroscopy (IBBCEAS) setup has been developed to simultaneously monitor temporal profiles of nitrate radical (NO3), nitrogen dioxide (NO2) and ozone (O3) concentrations in the atmosphere. The IBBCEAS setup performance was tested in an atmospheric chamber (8m3) at room temperature (296±2)K and dry conditions (RH<1%). The experiments were performed between 638nm and 672nm with a maximum mirror reflectivity of 99.991% leading to a maximum optical path length of 22km. The detection limits for NO3, NO2 and O3 were 7.9pptv, 9.0ppbv and 120ppbv, respectively, with an integration time of 60s.The temporal profiles of NO3, NO2 and O3 concentrations were simultaneously recorded during the NO2+O3 reaction and compared to those calculated from chemical simulations. The experimental and simulated data were in good accordance and demonstrate that the IBBCEAS is an effective technique to monitor in-situ and in real time multiple species concentrations (NO3, NO2 and O3). This technique presents the sensitivity and temporal resolution required for measurements in the atmosphere (both indoor and outdoor) and has also a large potential for laboratory studies in atmospheric simulation chamber. To our knowledge, this is the first time that an IBBCEAS instrument is used in a simulation chamber to follow NO3, NO2, and O3 concentrations during chemical reactions.