Applied Physics B

, Volume 106, Issue 4, pp 987–997 | Cite as

Wavelength-modulation-spectroscopy for real-time, in situ NO detection in combustion gases with a 5.2 μm quantum-cascade laser

  • X. Chao
  • J. B. Jeffries
  • R. K. Hanson


A mid-infrared absorption strategy with calibration-free wavelength-modulation-spectroscopy (WMS) has been developed and demonstrated for real-time, in situ detection of nitric oxide in particulate-laden combustion-exhaust gases up to temperatures of 700 K. An external-cavity quantum-cascade laser (ECQCL) near 5.2 μm accessed the fundamental absorption band of NO, and a wavelength-scanned, 1f-normalized WMS with second-harmonic detection (WMS-2f/1f) strategy was developed. Due to the external-cavity laser architecture, large nonlinear intensity modulation (IM) was observed when the wavelength was modulated by injection-current modulation, and the IM indices were also found to be strongly wavelength-dependent as the center wavelength was scanned with piezoelectric tuning of the cavity. A quantitative model of the 1f-normalized WMS-2f signal was developed and validated under laboratory conditions. A sensor was subsequently designed, built and demonstrated for real-time, in situ measurements of NO across a 3 m path in the particulate-laden exhaust of a pulverized-coal-fired power plant boiler. The 1f-normalized WMS-2f method proved to have better noise immunity for non-absorption transmission, than wavelength-scanned direct absorption. A 0.3 ppm-m detection limit was estimated using the R15.5 transition near 1927 cm−1 with 1 s averaging. Mid-infrared QCL-based NO absorption with 1f-normalized WMS-2f detection shows excellent promise for practical sensing in the combustion exhaust.


Nitric Oxide Intensity Modulation Direct Absorption SNCR Combustion Exhaust 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



Support was provided by the Electric Power Research Institute with Mr. Richard Himes as program manager and the Air Force Office of Scientific Research with Dr. Julian Tishkoff as program manager. We thank Dr. Michael Radunsky and Dr. Sam Crivello of Daylight Solutions for their useful comments on an early version of the manuscript.


  1. 1.
    US Environmental Protection Agency, National air quality and emissions trends report, Special Studies ed., Sept, 2003, available at
  2. 2.
    R.K. Hanson, Proc. Combust. Inst. 33, 1 (2011) CrossRefGoogle Scholar
  3. 3.
    P.K. Falcone, R.K. Hanson, C.H. Kruger, Combust. Sci. Technol. 35, 81 (1983) CrossRefGoogle Scholar
  4. 4.
    K.C. Smyth, D.R. Crosley, in Applied Combustion Diagnostics, ed. by K. Kohse-Höinghaus, J.B. Jeffries (Taylor and Francis, London 2002), pp. 9–68, Chap. 2 Google Scholar
  5. 5.
    T.N. Anderson, R.P. Lucht, S. Priyadarsan, K. Annamalai, J.A. Caton, Appl. Optim. 46, 3946 (2007) ADSCrossRefGoogle Scholar
  6. 6.
    J.B. McManus, J.H. Shorter, D.D. Nelson, M.S. Zahniser, D.E. Glenn, R.M. McGovern, Appl. Phys. B 92, 387 (2008) ADSCrossRefGoogle Scholar
  7. 7.
    M.S. Zahniser, D.D. Nelson, J.B. McManus, S.C. Herndon, E.C. Wood, J.H. Shorter, B.H. Lee, G.W. Santoni, R. Jimenez, B.C. Daube, S. Park, E.A. Kort, S.C. Wofsy, Proc. of SPIE 7222, 72220H (2009) ADSCrossRefGoogle Scholar
  8. 8.
    V.L. Kasyutich, R.K. Raja Ibrahim, P.A. Martin, Infrared Phys. Technol. 53, 381 (2010) ADSCrossRefGoogle Scholar
  9. 9.
    V.L. Kasyutich, R.J. Holdsworth, P.A. Martin, J. Phys. Conf. Ser. 157, 012006 (2009) ADSCrossRefGoogle Scholar
  10. 10.
    G. Hancock, J.H. van Helden, R. Peverall, G.A.D. Ritchie, R.J. Walker, Appl. Phys. Lett. 94, 201110 (2009) ADSCrossRefGoogle Scholar
  11. 11.
    Y.A. Bakhirkin, A.A. Kosterev, C. Roller, R.F. Curl, F.K. Tittel, Appl. Optim. 43, 2257 (2004) ADSCrossRefGoogle Scholar
  12. 12.
    X. Chao, J.B. Jeffries, R.K. Hanson, Proc. Combust. Inst. 33, 725 (2011) CrossRefGoogle Scholar
  13. 13.
    A.A. Kosterev, C. Roller, F.K. Tittel, W. Flory, in OSA/CLEO (2003) Google Scholar
  14. 14.
    G. Wysocki, A.A. Kosterev, F.K. Tittel, Appl. Phys. B 80, 617 (2005) ADSCrossRefGoogle Scholar
  15. 15.
    B.W.M. Moeskops, S.M. Cristescu, F.J.M. Harren, Optim. Lett. 31, 823 (2006) ADSCrossRefGoogle Scholar
  16. 16.
    W.H. Weber, J.T. Remillard, R.E. Chase, J.F. Richert, F. Capasso, C. Gmachl, A.L. Hutchinson, D.L. Sivco, J.N. Baillargeon, A.Y. Cho, Appl. Spectrosc. 56, 706 (2002) ADSCrossRefGoogle Scholar
  17. 17.
    D.T. Cassidy, J. Reid, Appl. Optim. 21, 1185 (1982) ADSCrossRefGoogle Scholar
  18. 18.
    H. Li, G.B. Rieker, X. Liu, J.B. Jeffries, R.K. Hanson, Appl. Optim. 45, 1052 (2006) ADSCrossRefGoogle Scholar
  19. 19.
    G.B. Rieker, X. Liu, H. Li, J.B. Jeffries, R.K. Hanson, Appl. Phys. B 87, 169 (2007) ADSCrossRefGoogle Scholar
  20. 20.
    G.B. Rieker, J.B. Jeffries, R.K. Hanson, Appl. Phys. B 94, 51 (2009) ADSCrossRefGoogle Scholar
  21. 21.
    G.B. Rieker, J.B. Jeffries, R.K. Hanson, Appl. Optim. 48, 5546 (2009) CrossRefGoogle Scholar
  22. 22.
    J. Reid, D. Labrie, Appl. Phys. B 26, 203 (1981) ADSCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  1. 1.High Temperature Gasdynamics Laboratory, Department of Mechanical EngineeringStanford UniversityStanfordUSA

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