Applied Physics B

, Volume 72, Issue 1, pp 121–125

Isotopic ratio measurement of methane in ambient air using mid-infrared cavity leak-out spectroscopy

  • H. Dahnke
  • D. Kleine
  • W. Urban
  • P. Hering
  • M. Mürtz
Article

DOI: 10.1007/s003400000509

Cite this article as:
Dahnke, H., Kleine, D., Urban, W. et al. Appl Phys B (2001) 72: 121. doi:10.1007/s003400000509

Abstract.

We report on infrared laser spectroscopic measurements of the isotopic composition of methane (12CH4, 13CH4) in natural air samples with a cavity ring-down technique. A CO overtone sideband laser is utilized to excite a high-finesse cavity which provides an effective optical absorption path length of 3.6 km. We achieved a detection limit of 105 ppt methane in ambient air using an integration time of 20 s. This corresponds to a minimum detectable absorption of 1.9×10-9 /cm. Rapid determination of the 13C/12Cisotopic ratio of methane in ambient air without sample preconcentration or gas processing is realized. The present system requires only few minutes for an isotopic ratio measurement with a precision of 11%o .

PACS: 07.88.+y; 42.62.Fi; 07.57.Ty 

Copyright information

© Springer-Verlag 2000

Authors and Affiliations

  • H. Dahnke
    • 1
  • D. Kleine
    • 1
  • W. Urban
    • 2
  • P. Hering
    • 1
  • M. Mürtz
    • 1
  1. 1.Institut für Lasermedizin, Universität Düsseldorf, 40225 Düsseldorf, GermanyDE
  2. 2.Institut für Angewandte Physik, Universität Bonn, 53115 Bonn, GermanyDE

Personalised recommendations