Differential Optical-absorption Spectroscopy (doas) System For Urban Atmospheric-pollution Monitoring

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Edner, H ; Ragnarson, P ; Spannare, S ; Svanberg, Sune (1993)
  • Publisher: Optical Society of America
  • Journal: (issn: 0740-3224)
  • Related identifiers: doi: 10.1364/AO.32.000327
  • Subject: Atom and Molecular Physics and Optics | Atom- och molekylfysik och optik

We describe a fully computer-controlled differential optical absorption spectroscopy system for atmospheric air pollution monitoring. A receiving optical telescope can sequentially tune in to light beams from a number of distant high-pressure Xe lamp light sources to cover the area of a medium-sized city. A beam-finding servosystem and automatic gain control permit unattended long-time monitoring. Using an astronomical code, we can also search and track celestial sources. Selected wavelength regions are rapidly and repetitively swept by a monochromator to sensitively record the atmospheric absorption spectrum while avoiding the detrimental effects of atmospheric turbulence. By computer fitting to stored laboratory spectra, we can evaluate the path-averaged concentration of a number of important pollutants such as NO2, SO2, and O3. A measurement of NH3 and NO close to the UV limit is also demonstrated.
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