Validation of the calibration of a laser-induced fluorescence instrument for the measurement of OH radicals in the atmosphere W. J. Bloss1, J. D. Lee1, C. Bloss1, D. E. Heard1, M. J. Pilling1, K. Wirtz2, M. Martin-Reviejo2, and M. Siese3 1Department of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK 2Fundación CEAM, EUPHORE Laboratories, C/ Charles Darwin 14, Parque Technológico, 46980 Paterna, Valencia, Spain 3Institut für Chemie und Dynamik der Geosphäre, Institut II: Troposphäre, Forschungszentrum Jülich, D-52425 Jülich, Germany
Abstract. An assessment of the accuracy of OH concentrations measured in a smog
chamber by a calibrated laser-induced fluorescence (LIF) instrument has been
made, in the course of 9 experiments performed to study the photo-oxidation
of benzene, toluene, 1,3,5-trimethylbenzene, para-xylene, ortho-cresol and ethene at
the European Photoreactor facility (EUPHORE). The LIF system was calibrated
via the water photolysis / ozone actinometry approach. OH concentrations were
inferred from the instantaneous rate of removal of each hydrocarbon species
(measured by FTIR or HPLC) via the appropriate rate coefficient for their
reaction with OH, and compared with those obtained from the LIF system. Good
agreement between the two approaches was found for all species with the
exception of 1,3,5-trimethylbenzene, for which OH concentrations inferred
from hydrocarbon removal were a factor of 3 lower than those measured by the
LIF system. From the remaining 8 experiments, an overall value of 1.15±0.13 (±1σ) was obtained for [OH]LIF / [OH]Hydrocarbon Decay, compared with the estimated uncertainty in the accuracy of the
water photolysis / ozone actinometry OH calibration technique of 26% (1σ).
Citation: Bloss, W. J., Lee, J. D., Bloss, C., Heard, D. E., Pilling, M. J., Wirtz, K., Martin-Reviejo, M., and Siese, M.: Validation of the calibration of a laser-induced fluorescence instrument for the measurement of OH radicals in the atmosphere, Atmos. Chem. Phys., 4, 571-583, doi:10.5194/acp-4-571-2004, 2004.