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.

© 1991 Optical Society of America