Concentration measurements of ozone in the 1200-300 ppbv range: an intercomparison between the BNM ultraviolet standard and infrared methods

摘要

Simultaneous ultraviolet (UV) and infrared (IR) measurements of ozone concentration in air in the 1200-300ppbv range have been per-formed using the ultraviolet absorption in the Hartley band at 0.2537 mum and the infrared absorption of a doublet at 9.507 mum in the nu(3) vibration-rotation band. Infrared concentration measurements were achieved using the tunable diode laser spectrometer of LPMA in Paris with interferometric control of the emitted wavelength while the UV concentration measurements were performed with the 49PS Megatec ozone generator of the Bureau National de Metrologie (BNM). The simultaneous recording of spectra of a reference cell filled with pure distilled ozone and of a low concentration mixture inside a long absorbing path Herriott cell allows to carry out infrared concentration measurements with an accuracy of the same order as the ultraviolet ones and provides the instrumental parameters of the spectrometer corresponding to each concentration measurement, which reduces systematic effots.Within the respective absolute uncertainties proper to the two techniques, no systematic discrepancy was evidenced between the IR and the UV measurements. The ozone ultraviolet absorption coefficient value determined by Hearn (308.3 +/- 4 cm(-1) atm(-1)) and used by the BNM and the National Institute of Standards and Technology (NIST) is confirmed by the present work. (C) 2004 Elsevier B.V. All rights reserved.