Detection of Minor Tropospheric Constituents using Fourier Transform Spectroscopy

Abstract

In the frame of TOPAS (Tropospheric OPtical Absorption Spectroscopy), an EURO-TRAC subproject supported by the Belgian State - Prime Minister’s Service - Science Policy Office and the ”Fond National de la Recherche Scientique”, a long path (788 m) absorption system has been constructed on the urban site of the campus of the Université Libre de Bruxelles. It consists of a Xenon high pressure emission source connected to a 30 cm Cassegrain type telescope. A parabolic mirror placed at a distance of 394 m reflects the light back into a similar telescope connected to a high resolution Fourier Transform spectrometer BRUKER IFS120HR. The two telescopes are mounted on alignment devices and the external mirror is equipped with a driving system operated from the laboratory. This system has been in operation since October 1990. Absorption structures of O2, O3, NO2 and SO2 have been observed in the UV region (25000-45000 cm-1). The spectra are recorded at a dispersion of 8 cm-1.