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| Titel |
Real time tracing of the kinetic process of NO3, N2O5 and NO2 with VOCs by long optical pathlength absorption spectroscopy |
| VerfasserIn |
Hongming YI, Tao Wu, Amélie Lauraguais, Vladimir Semenov, Cécile Coeur-Tourneur, Eric Fertein, Xiaoming Gao, Weidong Chen |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250100265
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| Publikation (Nr.) |
 EGU/EGU2014-16166.pdf |
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| Zusammenfassung |
| Nitrate radical (NO3) and dinitrogen pentoxide (N2O5, formed through the reaction of NO3 with NO2 and is a large reservoir for NO3) are two key intermediates components in atmospheric nitrogen chemistry [1]. They affect directly the oxidation capacity of the atmosphere through reaction of NO3 with volatile organic compounds (VOCs). It’s highly desirable to be able to perform in-situ, simultaneous and continuous monitoring of NO3 and N2O5 concentrations with high selectivity and fast response time. N2O5 is usually indirectly measured via optical measurement of NO3 after thermal dissociation of N2O5 to NO3 [2]. In this paper, we report on the recent development and application of optical method for in situ direct concentration measurements of NO3 and N2O5 in smog chamber. NO3 (as well as NO2) were simultaneously measured by open-path incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) [3] based on a light emitted diode operating in the range of 635-675 nm, and N2O5 was monitored by means of open-path multi-pass absorption spectroscopy of an external cavity quantum cascade laser tunable from 1223 to 1263 cm-1 (~8 µm). Reaction of NO3 with VOCs (such as isoprene, formaldehyde, 2-methoxyphenal) as well as the equilibrium between NO3 and N2O5 during the VOCs oxidation by NO3 radical have been on-line traced with high temporal resolution: 1 s for NO3-NO2 and 25 s for N2O5. Experimental detail and preliminary results will be presented. Our present work demonstrated that modern photonic technologies can provide a direct and highly selective means for chemical kinetic study, for instance, bringing insight into reactive uptake for NO3 and N2O5 on the organic particles [4], which remain still unexplored with few exceptions.
References
[1] Paul S. Monks, "Gas-phase radical chemistry in the troposphere", Chem. Soc. Rev. 34 (2005) 376–395.
[2] R.M. Varma, S.M. Ball, T. Brauers, H.-P. Dorn, U. Heitmann, R.L. Jones, U. Platt, D. Pöhler, A.A. Ruth, A.J.L. Shillings, J. Thieser, A. Wahner, and D.S. Venables, “Light extinction by Secondary Organic Aerosol: an intercomparison of three broadband cavity spectrometers”, Atmos. Meas. Tech. Discuss. 6 (2013) 6685–6727.
[3] T. Wu, C. Coeur-Turneur, G. Dhont, A. Cassez, E. Fertein, X. He, W. Chen, “Simultaneous monitoring of temporal profiles of NO3, NO2 and O3 by IBBCEAS for atmospheric applications”, J. Quant. Spectrosc. Radiat. Transfer 133 (2013) 199-205.
[4] S Brown, T. Ryerson, A. Wollny, C. Brock, R. Peltier, A. Sullivan, R. Weber, W. Dubé, M. Trainer, J. Meagher, F. Fehsenfeld, A. Ravishankara, “Variability in nocturnal nitrogen oxide processing and its role in regional air quality”, Science 311 (2006) 67-70 |
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