Seminar Ozean, Eis, Atmosphäre

Termin: 20.11.2001

Referent/in: Patrick Rairoux, Lyon, France

Titel: Cavity Ringdown

Cavity Ring Down Spectroscopy (CRDS) is a direct absorption technique, which can be performed with pulsed or continuous light sources and has a significantly higher sensitivity than obtainable in conventional absorption spectroscopy. The CRDS technique is based upon the mesurement of the rate of absorption rather than the magnitude of absorption of a light pulse confined in a closed optical cavity with a high Q factor. The advantage over normal absorption spectroscopy results from, firstly, the intrinsic insensitivity to light source intensity fluctuations and, secondly, the extremely long effective path lengths (many kilometres) that can be realised in stable optical cavities. In the last decade, it has been shown that the CRDS technique is especially powerful in gas-phase chemistry for measurements of either strong absorptions of species present in trace amounts or weak absorptions of abundant species. In this talk, the current knowledge will be reviewed and different applications of the technique will be presented and discussed.