Peroxy radical detection for airborne atmospheric measurements using cavity enhanced absorption spectroscopy of NO<sub>2</sub>
Author:
Horstjann M., D. Andrés Hernández M., Nenakhov V., Chrobry A., P. Burrows J.ORCID
Abstract
Abstract. Development of an airborne instrument for the determination of peroxy radicals (PeRCEAS – Peroxy Radical Cavity Enhanced Absorption Spectroscopy) is reported. Ambient peroxy radicals (HO2 and RO2, R being an organic chain) are converted to NO2 by adding NO, and are recycled through subsequent reaction with CO and O2, thus forming a chain reaction with an amplification factor called chain length. The concentration of NO2 is measured by continuous-wave cavity ring-down spectroscopy (CRDS) using an extended cavity diode laser at 409 nm. Optical feedback from a V-shaped cavity optimizes resonator transmission and allows for a simple detector set-up. CRDS directly yields absorption coefficients, thus providing NO2 concentrations without additional calibration. The optimum 1σ detection limit is 0.3 ppbv at an averaging time of 40 s and an inlet pressure of 300 mbar, corresponding to a concentration of 2 × 109 molecules cm−3. The calibration of the PeRCEAS chain length at an inlet pressure of 300 mbar yields a value of 120 ± 7. The peroxy radical 1σ detection limit for an averaging time of 120 s and a chain length of 120 is ~3 pptv.
Publisher
Copernicus GmbH
Reference40 articles.
1. Allan, D. W.: Statistics of atomic frequency standards, Proc. IEEE, 54, 221–230, 1966. 2. Andrés Hernández, M. D., Burkert, J., Reichert, L., Stöbener, D., Meyer-Arnek, J., and Burrows, J. P.: Marine boundary layer peroxy radical chemistry during the AEROSOLS99 campaign: measurements and analysis, J. Geophys. Res., 106, 20833–20846, 2001. 3. Andrés-Hernández, M. D., Kartal, D., Reichert, L., Burrows, J. P., Meyer Arnek, J., Lichtenstern, M., Stock, P., and Schlager, H.: Peroxy radical observations over West Africa during AMMA 2006: photochemical activity in the outflow of convective systems, Atmos. Chem. Phys., 9, 3681–3695, https://doi.org/10.5194/acp-9-3681-2009, 2009. 4. Andrés-Hernández, M. D., Stone, D., Brookes, D. M., Commane, R., Reeves, C. E., Huntrieser, H., Heard, D. E., Monks, P. S., Burrows, J. P., Schlager, H., Kartal, D., Evans, M. J., Floquet, C. F. A., Ingham, T., Methven, J., and Parker, A. E.: Peroxy radical partitioning during the AMMA radical intercomparison exercise, Atmos. Chem. Phys., 10, 10621–10638, https://doi.org/10.5194/acp-10-10621-2010, 2010. 5. Andrés-Hernández, M. D., Kartal, D., Crowley, J. N., Sinha, V., Regelin, E., Martínez-Harder, M., Nenakhov, V., Williams, J., Harder, H., Bozem, H., Song, W., Thieser, J., Tang, M. J., Hosaynali Beigi, Z., and Burrows, J. P.: Diel peroxy radicals in a semi-industrial coastal area: nighttime formation of free radicals, Atmos. Chem. Phys., 13, 5731–5749, https://doi.org/10.5194/acp-13-5731-2013, 2013.
|
|