Atmospheric gas trace detection with ultrashort pulses or white light continuum

Summary form only given. Gas pollutants in the atmosphere are present always with very low concentration (typically from one molecule per million molecules to one per billion). Previous experiments have in common that they work on a very narrow spectrum covering one or a few molecular absorption lines. We have coupled ultrashort sources such as femtosecond pulses or whitelight continuum, a multipass cell to realize a long optical path and a CCD camera spectrometer in order to detect gas traces in the visible and ultraviolet regions in ambient air at atmospheric pressure. The experiment has been tested in the visible range on reference oxygen bands and was proved to be sufficiently sensitive to detect the weak oxygen lines near 690 nm with an absorption cross section.