Applied Physics B

, 92:451

High precision and continuous field measurements of δ13C and δ18O in carbon dioxide with a cryogen-free QCLAS

  • B. Tuzson
  • J. Mohn
  • M.J. Zeeman
  • R.A. Werner
  • W. Eugster
  • M.S. Zahniser
  • D.D. Nelson
  • J.B. McManus
  • L. Emmenegger
Article

DOI: 10.1007/s00340-008-3085-4

Cite this article as:
Tuzson, B., Mohn, J., Zeeman, M. et al. Appl. Phys. B (2008) 92: 451. doi:10.1007/s00340-008-3085-4

Abstract

The present paper describes a compact and cryogen-free, quantum cascade laser based absorption spectrometer (QCLAS) designed for in situ, continuous and high precision isotope ratio measurements of atmospheric CO2. The mobile instrument incorporates several new features including a novel astigmatic multi-pass cell assembly, a quasi-room temperature quantum cascade laser, thermoelectrically cooled detectors as well as a new retrieval approach. The combination of these features now makes it possible to measure isotope ratios of ambient CO2 with a precision of 0.03 and 0.05‰ for δ13C and δ18O, respectively, using a 100 s integration time. A robust and optimized calibration procedure was developed to bring the retrieved isotope ratios on an absolute scale. This assures an accuracy better than 0.1‰ under laboratory conditions. The instrument performance was also assessed in a field campaign in which the spectrometer operated autonomously and provided mixing ratio values for the main three CO2 isotopologues at one second time resolution. An accuracy of 0.2‰ was routinely obtained for both isotope ratios during the entire period. The results were in excellent agreement with the standard laboratory-based isotope ratio mass spectrometer measurements made on field-collected flask samples. A few illustrative examples are used to depict the potential of this optical method in atmosphere–biosphere research.

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • B. Tuzson
    • 1
  • J. Mohn
    • 1
  • M.J. Zeeman
    • 2
  • R.A. Werner
    • 2
  • W. Eugster
    • 2
  • M.S. Zahniser
    • 3
  • D.D. Nelson
    • 3
  • J.B. McManus
    • 3
  • L. Emmenegger
    • 1
  1. 1.Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory for Air Pollution and Environmental TechnologyDübendorfSwitzerland
  2. 2.Institute of Plant Sciences, Grassland Science GroupETH ZurichZürichSwitzerland
  3. 3.Aerodyne Research Inc.BillericaUSA