Simultaneous monitoring of temporal profiles of NO_3, NO_2 and O_3 by incoherent broadband cavity enhanced absorption spectroscopy for atmospheric applications

摘要

An Incoherent Broadband Cavity Enhanced Absorption Spectroscopy (IBBCEAS) setup has been developed to simultaneously monitor temporal profiles of nitrate radical (NO_3)' nitrogen dioxide (NO_2) and ozone (O_3) concentrations in the atmosphere. The IBBCEAS setup performance was tested in an atmospheric chamber (8 m~3) at room temperature (296 ± 2) K and dry conditions (RH < 1%). The experiments were performed between 638 nm and 672 nm with a maximum mirror reflectivity of 99.991% leading to a maximum optical path length of 22 km. The detection limits for NO_3, NO_2 and O_3 were 7.9 pptv, 9.0 ppbv and 120 ppbv, respectively, with an integration time of 60 s. 2The temporal profiles of NO_3, NO_2 and O_3 concentrations were simultaneously recorded during the NO_2 + O_3 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 (NO_3, NO_2 and O_3). 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 NO_3, NO_2, and O_3 concentrations during chemical reactions.