title: Real-time detection of 13CH4 in ambient air by use of mid-infrared cavity leak-out spectroscopy.
abstract: We report on spectroscopic real-time detection of (13)CH(4) in ambient air. Our measurements were carried out by means of cavity leak-out absorption spectroscopy employing a tunable cw laser in the mid-infrared spectral region near lambda = 3 microm. A CO laser in combination with tunable microwave sideband generation was used as the light source. Using a 50-cm-long ringdown cell with R = 99.98% mirrors, we achieved a detection limit of 290 parts in 10(12) (ppt) (13)CH(4) in ambient air (integration time, 100 s). The corresponding noise-equivalent absorption coefficient was 5 x 10(-9)/cm.
authors: Institut für Lasermedizin, Universität Düsseldorf, Universitätsstrasse 1, D-40225 Düsseldorf, Germany.
authors: D
authors: D
authors: Kleine
authors: H
authors: H
authors: Dahnke
authors: W
authors: W
authors: Urban
authors: P
authors: P
authors: Hering
authors: M
authors: M
authors: Mürtz