Real-time trace-level detection of carbon dioxide and ethylene in car exhaust gases

M T McCulloch, N Langford, G Duxbury

Research output: Contribution to journalArticle

41 Citations (Scopus)


A direct-absorption spectrometer, based on a pulsed, distributed feedback, quantum cascade laser with a 10.26-μ m wavelength and an astigmatic Herriott cell with a 66-m path length, has been developed for high-resolution IR spectroscopy. This spectrometer utilizes the intrapulse method, an example of sweep integration, in which the almost linear wavelength up-chirp obtained from a distributed feedback, quantum cascade laser yields a spectral microwindow of as many as 2.5 wave numbers/cm(-1). Within this spectral microwindow, molecular fingerprints can be monitored and recorded in real time. This system allows both the detection of carbon dioxide and ethylene and the real-time observation of the evolution of these gases in the exhaust by-products from several cars. © 2005 Optical Society of America.

Original languageEnglish
Pages (from-to)2887-2894
Number of pages8
JournalApplied Optics
Issue number14
Publication statusPublished - 10 May 2005



  • quantum-cascade laser
  • cigarette smoke
  • spectroscopy
  • cells
  • spectrometer

Cite this