Abstract

We describe and demonstrate a technique that enhances the sensitivity of a spectrometer for trace gas detection by employing wavelength modulation spectroscopy (WMS) and integrating the absolute value of the recorded spectra across multiple lines of the species. The sensitivity is further enhanced by conducting WMS with large modulation depths. This technique is demonstrated using a continuously tunable external cavity CW quantum cascade laser to record the second harmonic wavelength modulated spectra of NO2 across the peak of the R-branch from 1629.5 to 1633.9cm1. By integrating the absolute value of the resulting spectra, the detection sensitivity of NO2 is improved by a factor of 40 compared to the sensitivity achieved using single-line WMS with the same apparatus. By using this technique, we achieve a sensitivity of approximately 6  parts   in  109 (ppb) using a short-path cell (a 1m absorption cell with two passes).

© 2010 Optical Society of America

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  1. United States Environmental Protection Agency, “National air quality status and trends through 2007,” EPA-454/R-08-006 (2008).
  2. J. Hildenbrand, J. Herbst, J. Wöllenstein, and A. Lambrecht, “Explosive detection using infrared laser spectroscopy,” Proc. SPIE 7222, 72220B (2009).
    [CrossRef]
  3. T. H. Risby and S. F. Solga, “Current status of clinical breath analysis,” Appl. Phys. B 85, 421-426 (2006).
    [CrossRef]
  4. A. A. Kosterev, R. F. Curl, F. K. Tittel, M. Rochat, M. Beck, D. Hofstetter, and J. Faist, “Chemical sensing with pulsed QC-DFB lasers operating at 6.6 μm,” Appl. Phys. B 75, 351-357 (2002).
    [CrossRef]
  5. F. K. Tittel, Y. Bakhirkin, A. Kosterev, and G. Wysocki, “Recent advances in trace gas detection using quantum and interband cascade lasers,” Rev. Laser Eng. 34, 275-282 (2006).
  6. G. Wysocki, R. Curl, F. Tittel, R. Maulini, J. Billiard, and J. Faist, “Widely tunable mode-hop free external cavity quantum cascade laser for high resolution spectroscopic applications,” Appl. Phys. B 81, 769-777 (2005).
    [CrossRef]
  7. A. Karpf and G. N. Rao, “Absorption and wavelength modulation spectroscopy of NO2 using a tunable, external cavity continuous wave quantum cascade laser,” Appl. Opt. 48, 408-413 (2009).
    [CrossRef] [PubMed]
  8. J. Reid and D. Labrie, “Second-harmonic detection with tunable diode lasers--comparison of experiment and theory,” Appl. Phys. B 26, 203-210 (1981).
    [CrossRef]
  9. G. N. Rao, C. Gudipaty, and D. Martin, “Higher harmonic detection employing wavelength modulation spectroscopy and near infra-red diode lasers: an undergraduate experiment,” Am. J. Phys. 77, 821-825 (2009).
    [CrossRef]
  10. J. M. Hollas, High Resolution Spectroscopy, Second Edition (Wiley1998).
  11. A. Karpf and G. N. Rao, “Enhanced sensitivity for the detection of trace gases using multiple line integrated absorption spectroscopy,” Appl. Opt. 48, 5061-5066 (2009).
    [CrossRef] [PubMed]
  12. L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
    [CrossRef]
  13. C. N. Mikhailenko, Yu. L. Babikov, and V. F. Golovko, “Information-calculating system spectroscopy of atmospheric gases. The structure and main functions,” Atmos. Oceanic Opt. 18, 685-695 (2005).
  14. G. Hancock, J. H. van Helden, R. Peverall, G. A. D. Ritchie, and R. J. Walker, “Direct and wavelength modulation spectroscopy using a cw external cavity quantum cascade laser,” Appl. Phys. Lett. 94, 201110, doi: 10.1063/1.3141521 (2009).
    [CrossRef]
  15. G. Schilt, L. Thévenaz, and P. Robert, “Wavelength Modulation Spectroscopy: combined frequency and intensity modulation,” Appl. Opt. 42, 6728-6738 (2003).
    [CrossRef] [PubMed]
  16. H. Li, G. B. Rieker, X. Liu, J. B. Jeffries, and R. K. Hanson, “Extension of wavelength modulation depth for diode laser absorption measurements in high-pressure gases,” Appl. Opt. 45, 1052-1061 (2006).
    [CrossRef] [PubMed]
  17. National Aeronautic and Space Administration, “Earth fact sheet--terrestrial atmosphere,” http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html.
  18. E. De Tommasi, G. Casa, and L. Gianfrani, “High precision determinations of NH3 concentration by means of diode laser spectrometry at 2.005 μm,” Appl. Phys. B 85, 257-263 (2006).
    [CrossRef]
  19. E. Burkhard and J. Schwab, “Ambient gaseous ammonia: evaluation of continuous measurement methods suitable for routine deployment--final report” (New York State Energy Research and Development Authority, 2008).
  20. National Oceanic and Atmospheric Administration, “Average relative humidity,” http://lwf.ncdc.noaa.gov/oa/climate/online/ccd/avgrh.html.

2009 (5)

J. Hildenbrand, J. Herbst, J. Wöllenstein, and A. Lambrecht, “Explosive detection using infrared laser spectroscopy,” Proc. SPIE 7222, 72220B (2009).
[CrossRef]

G. Hancock, J. H. van Helden, R. Peverall, G. A. D. Ritchie, and R. J. Walker, “Direct and wavelength modulation spectroscopy using a cw external cavity quantum cascade laser,” Appl. Phys. Lett. 94, 201110, doi: 10.1063/1.3141521 (2009).
[CrossRef]

G. N. Rao, C. Gudipaty, and D. Martin, “Higher harmonic detection employing wavelength modulation spectroscopy and near infra-red diode lasers: an undergraduate experiment,” Am. J. Phys. 77, 821-825 (2009).
[CrossRef]

A. Karpf and G. N. Rao, “Absorption and wavelength modulation spectroscopy of NO2 using a tunable, external cavity continuous wave quantum cascade laser,” Appl. Opt. 48, 408-413 (2009).
[CrossRef] [PubMed]

A. Karpf and G. N. Rao, “Enhanced sensitivity for the detection of trace gases using multiple line integrated absorption spectroscopy,” Appl. Opt. 48, 5061-5066 (2009).
[CrossRef] [PubMed]

2006 (4)

E. De Tommasi, G. Casa, and L. Gianfrani, “High precision determinations of NH3 concentration by means of diode laser spectrometry at 2.005 μm,” Appl. Phys. B 85, 257-263 (2006).
[CrossRef]

H. Li, G. B. Rieker, X. Liu, J. B. Jeffries, and R. K. Hanson, “Extension of wavelength modulation depth for diode laser absorption measurements in high-pressure gases,” Appl. Opt. 45, 1052-1061 (2006).
[CrossRef] [PubMed]

T. H. Risby and S. F. Solga, “Current status of clinical breath analysis,” Appl. Phys. B 85, 421-426 (2006).
[CrossRef]

F. K. Tittel, Y. Bakhirkin, A. Kosterev, and G. Wysocki, “Recent advances in trace gas detection using quantum and interband cascade lasers,” Rev. Laser Eng. 34, 275-282 (2006).

2005 (3)

G. Wysocki, R. Curl, F. Tittel, R. Maulini, J. Billiard, and J. Faist, “Widely tunable mode-hop free external cavity quantum cascade laser for high resolution spectroscopic applications,” Appl. Phys. B 81, 769-777 (2005).
[CrossRef]

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

C. N. Mikhailenko, Yu. L. Babikov, and V. F. Golovko, “Information-calculating system spectroscopy of atmospheric gases. The structure and main functions,” Atmos. Oceanic Opt. 18, 685-695 (2005).

2003 (1)

2002 (1)

A. A. Kosterev, R. F. Curl, F. K. Tittel, M. Rochat, M. Beck, D. Hofstetter, and J. Faist, “Chemical sensing with pulsed QC-DFB lasers operating at 6.6 μm,” Appl. Phys. B 75, 351-357 (2002).
[CrossRef]

1981 (1)

J. Reid and D. Labrie, “Second-harmonic detection with tunable diode lasers--comparison of experiment and theory,” Appl. Phys. B 26, 203-210 (1981).
[CrossRef]

Babikov, Yu. L.

C. N. Mikhailenko, Yu. L. Babikov, and V. F. Golovko, “Information-calculating system spectroscopy of atmospheric gases. The structure and main functions,” Atmos. Oceanic Opt. 18, 685-695 (2005).

Bakhirkin, Y.

F. K. Tittel, Y. Bakhirkin, A. Kosterev, and G. Wysocki, “Recent advances in trace gas detection using quantum and interband cascade lasers,” Rev. Laser Eng. 34, 275-282 (2006).

Barbe, A.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Beck, M.

A. A. Kosterev, R. F. Curl, F. K. Tittel, M. Rochat, M. Beck, D. Hofstetter, and J. Faist, “Chemical sensing with pulsed QC-DFB lasers operating at 6.6 μm,” Appl. Phys. B 75, 351-357 (2002).
[CrossRef]

Benner, D. C.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Billiard, J.

G. Wysocki, R. Curl, F. Tittel, R. Maulini, J. Billiard, and J. Faist, “Widely tunable mode-hop free external cavity quantum cascade laser for high resolution spectroscopic applications,” Appl. Phys. B 81, 769-777 (2005).
[CrossRef]

Birk, M.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Brown, L. R.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Burkhard, E.

E. Burkhard and J. Schwab, “Ambient gaseous ammonia: evaluation of continuous measurement methods suitable for routine deployment--final report” (New York State Energy Research and Development Authority, 2008).

Carleer, M. R.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Casa, G.

E. De Tommasi, G. Casa, and L. Gianfrani, “High precision determinations of NH3 concentration by means of diode laser spectrometry at 2.005 μm,” Appl. Phys. B 85, 257-263 (2006).
[CrossRef]

Chackerian, C.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Chance, K.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Coudert, L. H.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Curl, R.

G. Wysocki, R. Curl, F. Tittel, R. Maulini, J. Billiard, and J. Faist, “Widely tunable mode-hop free external cavity quantum cascade laser for high resolution spectroscopic applications,” Appl. Phys. B 81, 769-777 (2005).
[CrossRef]

Curl, R. F.

A. A. Kosterev, R. F. Curl, F. K. Tittel, M. Rochat, M. Beck, D. Hofstetter, and J. Faist, “Chemical sensing with pulsed QC-DFB lasers operating at 6.6 μm,” Appl. Phys. B 75, 351-357 (2002).
[CrossRef]

Dana, V.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

De Tommasi, E.

E. De Tommasi, G. Casa, and L. Gianfrani, “High precision determinations of NH3 concentration by means of diode laser spectrometry at 2.005 μm,” Appl. Phys. B 85, 257-263 (2006).
[CrossRef]

Devi, V. M.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Faist, J.

G. Wysocki, R. Curl, F. Tittel, R. Maulini, J. Billiard, and J. Faist, “Widely tunable mode-hop free external cavity quantum cascade laser for high resolution spectroscopic applications,” Appl. Phys. B 81, 769-777 (2005).
[CrossRef]

A. A. Kosterev, R. F. Curl, F. K. Tittel, M. Rochat, M. Beck, D. Hofstetter, and J. Faist, “Chemical sensing with pulsed QC-DFB lasers operating at 6.6 μm,” Appl. Phys. B 75, 351-357 (2002).
[CrossRef]

Flaud, J.-M.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Gamache, R. R.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Gianfrani, L.

E. De Tommasi, G. Casa, and L. Gianfrani, “High precision determinations of NH3 concentration by means of diode laser spectrometry at 2.005 μm,” Appl. Phys. B 85, 257-263 (2006).
[CrossRef]

Goldman, A.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Golovko, V. F.

C. N. Mikhailenko, Yu. L. Babikov, and V. F. Golovko, “Information-calculating system spectroscopy of atmospheric gases. The structure and main functions,” Atmos. Oceanic Opt. 18, 685-695 (2005).

Gudipaty, C.

G. N. Rao, C. Gudipaty, and D. Martin, “Higher harmonic detection employing wavelength modulation spectroscopy and near infra-red diode lasers: an undergraduate experiment,” Am. J. Phys. 77, 821-825 (2009).
[CrossRef]

Hancock, G.

G. Hancock, J. H. van Helden, R. Peverall, G. A. D. Ritchie, and R. J. Walker, “Direct and wavelength modulation spectroscopy using a cw external cavity quantum cascade laser,” Appl. Phys. Lett. 94, 201110, doi: 10.1063/1.3141521 (2009).
[CrossRef]

Hanson, R. K.

Hartmann, J.-M.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Herbst, J.

J. Hildenbrand, J. Herbst, J. Wöllenstein, and A. Lambrecht, “Explosive detection using infrared laser spectroscopy,” Proc. SPIE 7222, 72220B (2009).
[CrossRef]

Hildenbrand, J.

J. Hildenbrand, J. Herbst, J. Wöllenstein, and A. Lambrecht, “Explosive detection using infrared laser spectroscopy,” Proc. SPIE 7222, 72220B (2009).
[CrossRef]

Hofstetter, D.

A. A. Kosterev, R. F. Curl, F. K. Tittel, M. Rochat, M. Beck, D. Hofstetter, and J. Faist, “Chemical sensing with pulsed QC-DFB lasers operating at 6.6 μm,” Appl. Phys. B 75, 351-357 (2002).
[CrossRef]

Hollas, J. M.

J. M. Hollas, High Resolution Spectroscopy, Second Edition (Wiley1998).

Jacquemart, D.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Jeffries, J. B.

Jucks, K. W.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Karpf, A.

Kosterev, A.

F. K. Tittel, Y. Bakhirkin, A. Kosterev, and G. Wysocki, “Recent advances in trace gas detection using quantum and interband cascade lasers,” Rev. Laser Eng. 34, 275-282 (2006).

Kosterev, A. A.

A. A. Kosterev, R. F. Curl, F. K. Tittel, M. Rochat, M. Beck, D. Hofstetter, and J. Faist, “Chemical sensing with pulsed QC-DFB lasers operating at 6.6 μm,” Appl. Phys. B 75, 351-357 (2002).
[CrossRef]

Labrie, D.

J. Reid and D. Labrie, “Second-harmonic detection with tunable diode lasers--comparison of experiment and theory,” Appl. Phys. B 26, 203-210 (1981).
[CrossRef]

Lambrecht, A.

J. Hildenbrand, J. Herbst, J. Wöllenstein, and A. Lambrecht, “Explosive detection using infrared laser spectroscopy,” Proc. SPIE 7222, 72220B (2009).
[CrossRef]

Li, H.

Liu, X.

Maki, A. G.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Mandin, J.-Y.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Martin, D.

G. N. Rao, C. Gudipaty, and D. Martin, “Higher harmonic detection employing wavelength modulation spectroscopy and near infra-red diode lasers: an undergraduate experiment,” Am. J. Phys. 77, 821-825 (2009).
[CrossRef]

Massie, S. T.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Maulini, R.

G. Wysocki, R. Curl, F. Tittel, R. Maulini, J. Billiard, and J. Faist, “Widely tunable mode-hop free external cavity quantum cascade laser for high resolution spectroscopic applications,” Appl. Phys. B 81, 769-777 (2005).
[CrossRef]

Mikhailenko, C. N.

C. N. Mikhailenko, Yu. L. Babikov, and V. F. Golovko, “Information-calculating system spectroscopy of atmospheric gases. The structure and main functions,” Atmos. Oceanic Opt. 18, 685-695 (2005).

Orphal, J.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Perrin, A.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Peverall, R.

G. Hancock, J. H. van Helden, R. Peverall, G. A. D. Ritchie, and R. J. Walker, “Direct and wavelength modulation spectroscopy using a cw external cavity quantum cascade laser,” Appl. Phys. Lett. 94, 201110, doi: 10.1063/1.3141521 (2009).
[CrossRef]

Rao, G. N.

Reid, J.

J. Reid and D. Labrie, “Second-harmonic detection with tunable diode lasers--comparison of experiment and theory,” Appl. Phys. B 26, 203-210 (1981).
[CrossRef]

Rieker, G. B.

Rinsland, C. P.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Risby, T. H.

T. H. Risby and S. F. Solga, “Current status of clinical breath analysis,” Appl. Phys. B 85, 421-426 (2006).
[CrossRef]

Ritchie, G. A. D.

G. Hancock, J. H. van Helden, R. Peverall, G. A. D. Ritchie, and R. J. Walker, “Direct and wavelength modulation spectroscopy using a cw external cavity quantum cascade laser,” Appl. Phys. Lett. 94, 201110, doi: 10.1063/1.3141521 (2009).
[CrossRef]

Robert, P.

Rochat, M.

A. A. Kosterev, R. F. Curl, F. K. Tittel, M. Rochat, M. Beck, D. Hofstetter, and J. Faist, “Chemical sensing with pulsed QC-DFB lasers operating at 6.6 μm,” Appl. Phys. B 75, 351-357 (2002).
[CrossRef]

Rothman, L. S.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Schilt, G.

Schwab, J.

E. Burkhard and J. Schwab, “Ambient gaseous ammonia: evaluation of continuous measurement methods suitable for routine deployment--final report” (New York State Energy Research and Development Authority, 2008).

Smith, M. A. H.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Solga, S. F.

T. H. Risby and S. F. Solga, “Current status of clinical breath analysis,” Appl. Phys. B 85, 421-426 (2006).
[CrossRef]

Tennyson, J.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Thévenaz, L.

Tittel, F.

G. Wysocki, R. Curl, F. Tittel, R. Maulini, J. Billiard, and J. Faist, “Widely tunable mode-hop free external cavity quantum cascade laser for high resolution spectroscopic applications,” Appl. Phys. B 81, 769-777 (2005).
[CrossRef]

Tittel, F. K.

F. K. Tittel, Y. Bakhirkin, A. Kosterev, and G. Wysocki, “Recent advances in trace gas detection using quantum and interband cascade lasers,” Rev. Laser Eng. 34, 275-282 (2006).

A. A. Kosterev, R. F. Curl, F. K. Tittel, M. Rochat, M. Beck, D. Hofstetter, and J. Faist, “Chemical sensing with pulsed QC-DFB lasers operating at 6.6 μm,” Appl. Phys. B 75, 351-357 (2002).
[CrossRef]

Tolchenov, R. N.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Toth, R. A.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

van Helden, J. H.

G. Hancock, J. H. van Helden, R. Peverall, G. A. D. Ritchie, and R. J. Walker, “Direct and wavelength modulation spectroscopy using a cw external cavity quantum cascade laser,” Appl. Phys. Lett. 94, 201110, doi: 10.1063/1.3141521 (2009).
[CrossRef]

Vander Auwera, J.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Varanasi, P.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Wagner, G.

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Walker, R. J.

G. Hancock, J. H. van Helden, R. Peverall, G. A. D. Ritchie, and R. J. Walker, “Direct and wavelength modulation spectroscopy using a cw external cavity quantum cascade laser,” Appl. Phys. Lett. 94, 201110, doi: 10.1063/1.3141521 (2009).
[CrossRef]

Wöllenstein, J.

J. Hildenbrand, J. Herbst, J. Wöllenstein, and A. Lambrecht, “Explosive detection using infrared laser spectroscopy,” Proc. SPIE 7222, 72220B (2009).
[CrossRef]

Wysocki, G.

F. K. Tittel, Y. Bakhirkin, A. Kosterev, and G. Wysocki, “Recent advances in trace gas detection using quantum and interband cascade lasers,” Rev. Laser Eng. 34, 275-282 (2006).

G. Wysocki, R. Curl, F. Tittel, R. Maulini, J. Billiard, and J. Faist, “Widely tunable mode-hop free external cavity quantum cascade laser for high resolution spectroscopic applications,” Appl. Phys. B 81, 769-777 (2005).
[CrossRef]

Am. J. Phys. (1)

G. N. Rao, C. Gudipaty, and D. Martin, “Higher harmonic detection employing wavelength modulation spectroscopy and near infra-red diode lasers: an undergraduate experiment,” Am. J. Phys. 77, 821-825 (2009).
[CrossRef]

Appl. Opt. (4)

Appl. Phys. B (5)

G. Wysocki, R. Curl, F. Tittel, R. Maulini, J. Billiard, and J. Faist, “Widely tunable mode-hop free external cavity quantum cascade laser for high resolution spectroscopic applications,” Appl. Phys. B 81, 769-777 (2005).
[CrossRef]

J. Reid and D. Labrie, “Second-harmonic detection with tunable diode lasers--comparison of experiment and theory,” Appl. Phys. B 26, 203-210 (1981).
[CrossRef]

T. H. Risby and S. F. Solga, “Current status of clinical breath analysis,” Appl. Phys. B 85, 421-426 (2006).
[CrossRef]

A. A. Kosterev, R. F. Curl, F. K. Tittel, M. Rochat, M. Beck, D. Hofstetter, and J. Faist, “Chemical sensing with pulsed QC-DFB lasers operating at 6.6 μm,” Appl. Phys. B 75, 351-357 (2002).
[CrossRef]

E. De Tommasi, G. Casa, and L. Gianfrani, “High precision determinations of NH3 concentration by means of diode laser spectrometry at 2.005 μm,” Appl. Phys. B 85, 257-263 (2006).
[CrossRef]

Appl. Phys. Lett. (1)

G. Hancock, J. H. van Helden, R. Peverall, G. A. D. Ritchie, and R. J. Walker, “Direct and wavelength modulation spectroscopy using a cw external cavity quantum cascade laser,” Appl. Phys. Lett. 94, 201110, doi: 10.1063/1.3141521 (2009).
[CrossRef]

Atmos. Oceanic Opt. (1)

C. N. Mikhailenko, Yu. L. Babikov, and V. F. Golovko, “Information-calculating system spectroscopy of atmospheric gases. The structure and main functions,” Atmos. Oceanic Opt. 18, 685-695 (2005).

J. Quant. Spectrosc. Radiat. Transfer (1)

L. S. Rothman, D. Jacquemart, A. Barbe, D. C. Benner, M. Birk, L. R. Brown, M. R. Carleer, C. Chackerian Jr., K. Chance, L. H. Coudert, V. Dana, V. M. Devi, J.-M. Flaud, R. R. Gamache, A. Goldman, J.-M. Hartmann, K. W. Jucks, A. G. Maki, J.-Y. Mandin, S. T. Massie, J. Orphal, A. Perrin, C. P. Rinsland, M. A. H. Smith, J. Tennyson, R. N. Tolchenov, R. A. Toth, J. Vander Auwera, P. Varanasi, and G. Wagner, “The HITRAN 2004 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005).
[CrossRef]

Proc. SPIE (1)

J. Hildenbrand, J. Herbst, J. Wöllenstein, and A. Lambrecht, “Explosive detection using infrared laser spectroscopy,” Proc. SPIE 7222, 72220B (2009).
[CrossRef]

Rev. Laser Eng. (1)

F. K. Tittel, Y. Bakhirkin, A. Kosterev, and G. Wysocki, “Recent advances in trace gas detection using quantum and interband cascade lasers,” Rev. Laser Eng. 34, 275-282 (2006).

Other (5)

United States Environmental Protection Agency, “National air quality status and trends through 2007,” EPA-454/R-08-006 (2008).

J. M. Hollas, High Resolution Spectroscopy, Second Edition (Wiley1998).

National Aeronautic and Space Administration, “Earth fact sheet--terrestrial atmosphere,” http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html.

E. Burkhard and J. Schwab, “Ambient gaseous ammonia: evaluation of continuous measurement methods suitable for routine deployment--final report” (New York State Energy Research and Development Authority, 2008).

National Oceanic and Atmospheric Administration, “Average relative humidity,” http://lwf.ncdc.noaa.gov/oa/climate/online/ccd/avgrh.html.

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Figures (5)

Fig. 1
Fig. 1

Plot of the integrated second harmonic ( 2 f ) wavelength modulation spectra versus pressure generated from simulated spectra based on the HITRAN database [12]. The peak value of the signal occurs at a pressure of about 100 mbar .

Fig. 2
Fig. 2

Schematic of the experimental setup used for WMS of NO 2 .

Fig. 3
Fig. 3

(a) Simulated NO 2 spectrum ( 50 ppm at 200 mbar ) for the R-branch between 1620 and 1645 cm 1 . Overlaid onto the spectrum are the water lines that match typical conditions in the mid-latitude United States during the summer months. This spectrum was used to select a region with a strong dense NO 2 spectrum that was free from interference due to water lines. (b) Close-up of the region that was recorded and integrated.

Fig. 4
Fig. 4

(a) Second harmonic WMS signal of the absorption spectrum of the doublet at 1629.52 cm 1 . The NO 2 concentration was 2.5 ± 0.38 ppm at a pressure of 110 ± 10 mbar . The second harmonic signals from other nearby multiplets can also be seen at 1630.1 cm 1 and in the region above 1630.7 cm 1 . (b) The noise content is shown for the same region and was obtained under the same operating conditions, but with an empty cell.

Fig. 5
Fig. 5

(a) Total second harmonic WMS signal versus con centration plot. The expected linear relationship between the integrated second harmonic WMS signal of the various concentra tions is seen. The y intercept is used to determine the sensitivity of detection. (b) Expanded scale of the low concentration region is employed to clearly display the low concentration data points.

Equations (15)

Equations on this page are rendered with MathJax. Learn more.

I ( ν ) = I 0 ( ν ) e α ( ν ) L ,
I ( ν ) = I 0 ( ν ) [ 1 α ( ν ) L ] .
ν ( t ) = ν ¯ + a cos ( ω t ) ,
I ( ν ) = I 0 ( ν ) [ 1 α ( ν ¯ + a cos ω t ) L ] .
α ( ν ¯ + a cos ω t ) = n = 0 H n ( ν ¯ ) cos n ω t ,
H n ( ν ¯ ) = 2 n 1 n ! a n d n α ( ν ) d ν n | ν = ν ¯ .
S = α ( ν ) L d ν .
ν ( t ) = ν ¯ + a cos ( ω t + ψ ) ,
I 0 ( t ) = I ¯ 0 [ 1 + i 0 cos ( ω t + ψ 1 ) + i 2 cos ( 2 ω t + ψ 2 ) ] ,
I ( ν ) = I 0 ( ν ) [ 1 α ( ν ) L ] = I 0 ( ν ) [ 1 P χ i L j S j φ j ] ,
α ( ν ¯ + a cos ω t ) = n = 0 H n ( ν ¯ , a ) cos n ω t ,
H n ( ν ¯ , a ) = P χ i L 2 π π π j S j φ j ( ν ¯ + a cos θ ) cos k θ d θ .
X 2 f = G I ¯ 0 2 [ H 2 + i 0 2 ( H 1 + H 3 ) cos ψ 1 + i 2 ( 1 + H 0 + H 4 2 ) cos ψ 2 ] ,
Y 2 f = G I ¯ 0 2 [ i 0 2 ( H 1 H 3 ) sin ψ 1 + i 2 ( 1 + H 0 H 4 2 ) sin ψ 2 ] .
R 2 f = X 2 f 2 + Y 2 f 2 .

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