Abstract

A tunable diode laser diagnostic based on spectrally resolved laser absorption has been developed to detect water vapor. The system uses a distributed feedback InGaAsP diode laser, emitting at ~ 1.38 μm. The diode laser is tuned in wavelength by modulation of the current, resulting in 1-cm−1 tuning at 80-Hz repetition rate. The directly measured absorption spectra yield values for water-vapor concentration and temperature, as well as a collision-broadening line shape. To our knowledge, we accurately determined required data for H2O line strengths and self-broadening coefficients for several spectral lines in a static cell filled with pure water vapor. The temperature and concentration of the water vapor present in laboratory room air and in the postflame gases above a methane–air flat flame burner have also been measured. These results agree well with calculated values and independent measurements.

© 1993 Optical Society of America

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References

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  1. E. C. Rea, R. K. Hanson, “Rapid laser-wavelength modulation spectroscopy used as a fast temperature measurement technique in hydrocarbon combustion,” Appl. Opt. 27, 4454–4464(1988).
    [CrossRef] [PubMed]
  2. A. Y. Chang, M. D. DiRosa, D. F. Davidson, R. K. Hanson, “Rapid tuning cw laser technique for measurements of gas velocity, temperature, pressure, density, and mass flux using NO,” Appl. Opt. 30, 3011–3022 (1991).
    [CrossRef] [PubMed]
  3. L. C. Philippe, R. K. Hanson, “Tunable diode laser absorption sensor for temperature and velocity measurements of O2 in air flows,” in Technical Digest, Twenty-Ninth Aerospace Sciences Meeting (American Institute of Aeronautics and Astronautics, Washington, D.C., 1991), paper 91-0360.
  4. D. T. Cassidy, “Trace gas detection using 1.3-μm InGaAsP diode laser transmitter modules,” Appl. Opt. 27, 610–614 (1988).
    [CrossRef] [PubMed]
  5. D. M. Bruce, D. T. Cassidy, “Detection of oxygen using short external cavity GaAs semiconductor diode lasers,” Appl. Opt. 29, 1327–1332 (1990).
    [CrossRef] [PubMed]
  6. W. Length, H. Gehrtz, “Sensitive detection of NO2 using high-frequency heterodyne spectroscopy with a GaAlAs diode laser,” Appl. Phys. Lett. 47, 1263–1265 (1985).
    [CrossRef]
  7. L.-G. Wang, D. A. Tate, H. Riris, T. F. Gallagher, “High-sensitivity frequency-modulation spectroscopy with a GaAlAs diode laser,” J. Opt. Soc. Am. B 6, 871–876 (1989).
    [CrossRef]
  8. N. Goldstein, S. Adler-Golden, J. Lee, F. Bien, “Measurement of molecular concentrations and line parameters using line-locked second harmonic spectroscopy with an AlGaAs diode laser,” Appl. Opt. 31, 3409–3415 (1992).
    [CrossRef] [PubMed]
  9. H. Sasada, K. Yamada, “Calibration lines of HCN in the 1.5-μm region,” Appl. Opt. 29, 3535–3547 (1990).
    [CrossRef] [PubMed]
  10. D. T. Cassidy, L. J. Bonnell, “Trace gas detection with short-external-cavity InGaAsP diode laser transmitter operating at 1.58 μm,” Appl. Opt. 27, 2688–2693 (1988).
    [CrossRef] [PubMed]
  11. A. C. Stanton, J. A. Silver, “Measurements in the HCL 3 ← 0 band using a near-IR InGaAsP diode laser,” Appl. Opt. 27, 5009–5015 (1988).
    [CrossRef] [PubMed]
  12. C. B. Carlisle, D. E. Cooper, “Tunable diode laser frequency modulation spectroscopy through an optical fiber: high sensitivity detection of water vapor,” Appl. Phys. Lett. 56, 805–807 (1990).
    [CrossRef]
  13. A. C. Stanton, D. S. Bomse, J. A. Silver, “A nonintrusive diagnostic for water vapor in high temperature flow fields,” Tech. Rep. R90-01, for National Aero-Space Plane Joint Program Office AFSC/NAC (Southwest Sciences, Inc., Santa Fe, N.M., 1991).
  14. M. P. Arroyo, R. K. Hanson, “Tunable diode laser absorption technique for detection of water vapor in aerodynamic flows,” in Technical Digest, Thirtieth Aerospace Sciences Meeting (American Institute of Aeronautics and Astronautics, Washington, D.C., 1992) paper 92-0510.
  15. hitran data base, 1992 ed. (Digital Product Section, National Climatic Center, National Oceanic and Atmospheric Administration, Federal Building, Asheville, N. C. 28801).
  16. G. Herzberg, Molecular Spectra and Molecular Structure II. Infrared and Raman Spectra of Polyatomic Molecules (Van Nostrand Reinhold, New York, 1945).
  17. L. S. Rothmann, R. R. Gamache, A. Goldman, L. R. Brown, R. A. Toth, H. M. Pickett, R. L. Poynter, J.-M. Flaud, C. Camy-Peyret, A. Barbe, N. Husson, C. P. Rinsland, M. A. H. Smith, “The hitran Database: 1986 edition,” Appl. Opt. 26, 4058–4097 (1987).
    [CrossRef]
  18. C. Delaye, J.-M. Hartmann, J. Taine, “Calculated tabulations of H2O line broadening by H2O, N2, O2, and CO2 at high temperature,” Appl. Opt. 28, 5080–5087 (1989).
    [CrossRef] [PubMed]
  19. R. A. Toth, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, Calif. 91109 (personal communication, 1992).
  20. J. M. Flaud, C. Camy-Peyret, J. P. Maillard, “Higher rovibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 2800–6200 cm−1,” Mol. Phys. 32, 499–521 (1976); C. Camy-Peyret, J. M. Flaud, J. P. Maillard, “Higher rovibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 6200 and 9100 cm−1,” Mol. Phys. 33, 1641–1650 (1977).
    [CrossRef]
  21. B. E. Grossmann, E. V. Browell, “Spectroscopy of water vapor in the 720-nm wavelength region: line strengths, self-induced pressure broadenings and shifts, and temperature dependence of linewidths and shifts,” J. Mol. Spectrosc. 136, 264–294 (1989); “Water-vapor line broadening and shifting by air, nitrogen, oxygen, and argon in the 720-nm wavelength region,” J. Mol. Spectrosc. 138, 562–595 (1989).
    [CrossRef]
  22. B. F. Ventrudo, D. T. Cassidy, “Operating characteristics of a tunable diode laser absorption spectrometer using short-external-cavity and DFB laser diodes,” Appl. Opt. 29, 5007–5013 (1990).
    [CrossRef] [PubMed]

1992 (1)

1991 (1)

1990 (4)

1989 (3)

B. E. Grossmann, E. V. Browell, “Spectroscopy of water vapor in the 720-nm wavelength region: line strengths, self-induced pressure broadenings and shifts, and temperature dependence of linewidths and shifts,” J. Mol. Spectrosc. 136, 264–294 (1989); “Water-vapor line broadening and shifting by air, nitrogen, oxygen, and argon in the 720-nm wavelength region,” J. Mol. Spectrosc. 138, 562–595 (1989).
[CrossRef]

C. Delaye, J.-M. Hartmann, J. Taine, “Calculated tabulations of H2O line broadening by H2O, N2, O2, and CO2 at high temperature,” Appl. Opt. 28, 5080–5087 (1989).
[CrossRef] [PubMed]

L.-G. Wang, D. A. Tate, H. Riris, T. F. Gallagher, “High-sensitivity frequency-modulation spectroscopy with a GaAlAs diode laser,” J. Opt. Soc. Am. B 6, 871–876 (1989).
[CrossRef]

1988 (4)

1987 (1)

1985 (1)

W. Length, H. Gehrtz, “Sensitive detection of NO2 using high-frequency heterodyne spectroscopy with a GaAlAs diode laser,” Appl. Phys. Lett. 47, 1263–1265 (1985).
[CrossRef]

1976 (1)

J. M. Flaud, C. Camy-Peyret, J. P. Maillard, “Higher rovibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 2800–6200 cm−1,” Mol. Phys. 32, 499–521 (1976); C. Camy-Peyret, J. M. Flaud, J. P. Maillard, “Higher rovibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 6200 and 9100 cm−1,” Mol. Phys. 33, 1641–1650 (1977).
[CrossRef]

Adler-Golden, S.

Arroyo, M. P.

M. P. Arroyo, R. K. Hanson, “Tunable diode laser absorption technique for detection of water vapor in aerodynamic flows,” in Technical Digest, Thirtieth Aerospace Sciences Meeting (American Institute of Aeronautics and Astronautics, Washington, D.C., 1992) paper 92-0510.

Barbe, A.

Bien, F.

Bomse, D. S.

A. C. Stanton, D. S. Bomse, J. A. Silver, “A nonintrusive diagnostic for water vapor in high temperature flow fields,” Tech. Rep. R90-01, for National Aero-Space Plane Joint Program Office AFSC/NAC (Southwest Sciences, Inc., Santa Fe, N.M., 1991).

Bonnell, L. J.

Browell, E. V.

B. E. Grossmann, E. V. Browell, “Spectroscopy of water vapor in the 720-nm wavelength region: line strengths, self-induced pressure broadenings and shifts, and temperature dependence of linewidths and shifts,” J. Mol. Spectrosc. 136, 264–294 (1989); “Water-vapor line broadening and shifting by air, nitrogen, oxygen, and argon in the 720-nm wavelength region,” J. Mol. Spectrosc. 138, 562–595 (1989).
[CrossRef]

Brown, L. R.

Bruce, D. M.

Camy-Peyret, C.

L. S. Rothmann, R. R. Gamache, A. Goldman, L. R. Brown, R. A. Toth, H. M. Pickett, R. L. Poynter, J.-M. Flaud, C. Camy-Peyret, A. Barbe, N. Husson, C. P. Rinsland, M. A. H. Smith, “The hitran Database: 1986 edition,” Appl. Opt. 26, 4058–4097 (1987).
[CrossRef]

J. M. Flaud, C. Camy-Peyret, J. P. Maillard, “Higher rovibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 2800–6200 cm−1,” Mol. Phys. 32, 499–521 (1976); C. Camy-Peyret, J. M. Flaud, J. P. Maillard, “Higher rovibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 6200 and 9100 cm−1,” Mol. Phys. 33, 1641–1650 (1977).
[CrossRef]

Carlisle, C. B.

C. B. Carlisle, D. E. Cooper, “Tunable diode laser frequency modulation spectroscopy through an optical fiber: high sensitivity detection of water vapor,” Appl. Phys. Lett. 56, 805–807 (1990).
[CrossRef]

Cassidy, D. T.

Chang, A. Y.

Cooper, D. E.

C. B. Carlisle, D. E. Cooper, “Tunable diode laser frequency modulation spectroscopy through an optical fiber: high sensitivity detection of water vapor,” Appl. Phys. Lett. 56, 805–807 (1990).
[CrossRef]

Davidson, D. F.

Delaye, C.

DiRosa, M. D.

Flaud, J. M.

J. M. Flaud, C. Camy-Peyret, J. P. Maillard, “Higher rovibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 2800–6200 cm−1,” Mol. Phys. 32, 499–521 (1976); C. Camy-Peyret, J. M. Flaud, J. P. Maillard, “Higher rovibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 6200 and 9100 cm−1,” Mol. Phys. 33, 1641–1650 (1977).
[CrossRef]

Flaud, J.-M.

Gallagher, T. F.

Gamache, R. R.

Gehrtz, H.

W. Length, H. Gehrtz, “Sensitive detection of NO2 using high-frequency heterodyne spectroscopy with a GaAlAs diode laser,” Appl. Phys. Lett. 47, 1263–1265 (1985).
[CrossRef]

Goldman, A.

Goldstein, N.

Grossmann, B. E.

B. E. Grossmann, E. V. Browell, “Spectroscopy of water vapor in the 720-nm wavelength region: line strengths, self-induced pressure broadenings and shifts, and temperature dependence of linewidths and shifts,” J. Mol. Spectrosc. 136, 264–294 (1989); “Water-vapor line broadening and shifting by air, nitrogen, oxygen, and argon in the 720-nm wavelength region,” J. Mol. Spectrosc. 138, 562–595 (1989).
[CrossRef]

Hanson, R. K.

A. Y. Chang, M. D. DiRosa, D. F. Davidson, R. K. Hanson, “Rapid tuning cw laser technique for measurements of gas velocity, temperature, pressure, density, and mass flux using NO,” Appl. Opt. 30, 3011–3022 (1991).
[CrossRef] [PubMed]

E. C. Rea, R. K. Hanson, “Rapid laser-wavelength modulation spectroscopy used as a fast temperature measurement technique in hydrocarbon combustion,” Appl. Opt. 27, 4454–4464(1988).
[CrossRef] [PubMed]

L. C. Philippe, R. K. Hanson, “Tunable diode laser absorption sensor for temperature and velocity measurements of O2 in air flows,” in Technical Digest, Twenty-Ninth Aerospace Sciences Meeting (American Institute of Aeronautics and Astronautics, Washington, D.C., 1991), paper 91-0360.

M. P. Arroyo, R. K. Hanson, “Tunable diode laser absorption technique for detection of water vapor in aerodynamic flows,” in Technical Digest, Thirtieth Aerospace Sciences Meeting (American Institute of Aeronautics and Astronautics, Washington, D.C., 1992) paper 92-0510.

Hartmann, J.-M.

Herzberg, G.

G. Herzberg, Molecular Spectra and Molecular Structure II. Infrared and Raman Spectra of Polyatomic Molecules (Van Nostrand Reinhold, New York, 1945).

Husson, N.

Lee, J.

Length, W.

W. Length, H. Gehrtz, “Sensitive detection of NO2 using high-frequency heterodyne spectroscopy with a GaAlAs diode laser,” Appl. Phys. Lett. 47, 1263–1265 (1985).
[CrossRef]

Maillard, J. P.

J. M. Flaud, C. Camy-Peyret, J. P. Maillard, “Higher rovibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 2800–6200 cm−1,” Mol. Phys. 32, 499–521 (1976); C. Camy-Peyret, J. M. Flaud, J. P. Maillard, “Higher rovibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 6200 and 9100 cm−1,” Mol. Phys. 33, 1641–1650 (1977).
[CrossRef]

Philippe, L. C.

L. C. Philippe, R. K. Hanson, “Tunable diode laser absorption sensor for temperature and velocity measurements of O2 in air flows,” in Technical Digest, Twenty-Ninth Aerospace Sciences Meeting (American Institute of Aeronautics and Astronautics, Washington, D.C., 1991), paper 91-0360.

Pickett, H. M.

Poynter, R. L.

Rea, E. C.

Rinsland, C. P.

Riris, H.

Rothmann, L. S.

Sasada, H.

Silver, J. A.

A. C. Stanton, J. A. Silver, “Measurements in the HCL 3 ← 0 band using a near-IR InGaAsP diode laser,” Appl. Opt. 27, 5009–5015 (1988).
[CrossRef] [PubMed]

A. C. Stanton, D. S. Bomse, J. A. Silver, “A nonintrusive diagnostic for water vapor in high temperature flow fields,” Tech. Rep. R90-01, for National Aero-Space Plane Joint Program Office AFSC/NAC (Southwest Sciences, Inc., Santa Fe, N.M., 1991).

Smith, M. A. H.

Stanton, A. C.

A. C. Stanton, J. A. Silver, “Measurements in the HCL 3 ← 0 band using a near-IR InGaAsP diode laser,” Appl. Opt. 27, 5009–5015 (1988).
[CrossRef] [PubMed]

A. C. Stanton, D. S. Bomse, J. A. Silver, “A nonintrusive diagnostic for water vapor in high temperature flow fields,” Tech. Rep. R90-01, for National Aero-Space Plane Joint Program Office AFSC/NAC (Southwest Sciences, Inc., Santa Fe, N.M., 1991).

Taine, J.

Tate, D. A.

Toth, R. A.

Ventrudo, B. F.

Wang, L.-G.

Yamada, K.

Appl. Opt. (11)

N. Goldstein, S. Adler-Golden, J. Lee, F. Bien, “Measurement of molecular concentrations and line parameters using line-locked second harmonic spectroscopy with an AlGaAs diode laser,” Appl. Opt. 31, 3409–3415 (1992).
[CrossRef] [PubMed]

H. Sasada, K. Yamada, “Calibration lines of HCN in the 1.5-μm region,” Appl. Opt. 29, 3535–3547 (1990).
[CrossRef] [PubMed]

D. T. Cassidy, L. J. Bonnell, “Trace gas detection with short-external-cavity InGaAsP diode laser transmitter operating at 1.58 μm,” Appl. Opt. 27, 2688–2693 (1988).
[CrossRef] [PubMed]

A. C. Stanton, J. A. Silver, “Measurements in the HCL 3 ← 0 band using a near-IR InGaAsP diode laser,” Appl. Opt. 27, 5009–5015 (1988).
[CrossRef] [PubMed]

D. T. Cassidy, “Trace gas detection using 1.3-μm InGaAsP diode laser transmitter modules,” Appl. Opt. 27, 610–614 (1988).
[CrossRef] [PubMed]

D. M. Bruce, D. T. Cassidy, “Detection of oxygen using short external cavity GaAs semiconductor diode lasers,” Appl. Opt. 29, 1327–1332 (1990).
[CrossRef] [PubMed]

E. C. Rea, R. K. Hanson, “Rapid laser-wavelength modulation spectroscopy used as a fast temperature measurement technique in hydrocarbon combustion,” Appl. Opt. 27, 4454–4464(1988).
[CrossRef] [PubMed]

A. Y. Chang, M. D. DiRosa, D. F. Davidson, R. K. Hanson, “Rapid tuning cw laser technique for measurements of gas velocity, temperature, pressure, density, and mass flux using NO,” Appl. Opt. 30, 3011–3022 (1991).
[CrossRef] [PubMed]

L. S. Rothmann, R. R. Gamache, A. Goldman, L. R. Brown, R. A. Toth, H. M. Pickett, R. L. Poynter, J.-M. Flaud, C. Camy-Peyret, A. Barbe, N. Husson, C. P. Rinsland, M. A. H. Smith, “The hitran Database: 1986 edition,” Appl. Opt. 26, 4058–4097 (1987).
[CrossRef]

C. Delaye, J.-M. Hartmann, J. Taine, “Calculated tabulations of H2O line broadening by H2O, N2, O2, and CO2 at high temperature,” Appl. Opt. 28, 5080–5087 (1989).
[CrossRef] [PubMed]

B. F. Ventrudo, D. T. Cassidy, “Operating characteristics of a tunable diode laser absorption spectrometer using short-external-cavity and DFB laser diodes,” Appl. Opt. 29, 5007–5013 (1990).
[CrossRef] [PubMed]

Appl. Phys. Lett. (2)

W. Length, H. Gehrtz, “Sensitive detection of NO2 using high-frequency heterodyne spectroscopy with a GaAlAs diode laser,” Appl. Phys. Lett. 47, 1263–1265 (1985).
[CrossRef]

C. B. Carlisle, D. E. Cooper, “Tunable diode laser frequency modulation spectroscopy through an optical fiber: high sensitivity detection of water vapor,” Appl. Phys. Lett. 56, 805–807 (1990).
[CrossRef]

J. Mol. Spectrosc. (1)

B. E. Grossmann, E. V. Browell, “Spectroscopy of water vapor in the 720-nm wavelength region: line strengths, self-induced pressure broadenings and shifts, and temperature dependence of linewidths and shifts,” J. Mol. Spectrosc. 136, 264–294 (1989); “Water-vapor line broadening and shifting by air, nitrogen, oxygen, and argon in the 720-nm wavelength region,” J. Mol. Spectrosc. 138, 562–595 (1989).
[CrossRef]

J. Opt. Soc. Am. B (1)

Mol. Phys. (1)

J. M. Flaud, C. Camy-Peyret, J. P. Maillard, “Higher rovibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 2800–6200 cm−1,” Mol. Phys. 32, 499–521 (1976); C. Camy-Peyret, J. M. Flaud, J. P. Maillard, “Higher rovibrational levels of H2O deduced from high resolution oxygen-hydrogen flame spectra between 6200 and 9100 cm−1,” Mol. Phys. 33, 1641–1650 (1977).
[CrossRef]

Other (6)

R. A. Toth, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, Calif. 91109 (personal communication, 1992).

L. C. Philippe, R. K. Hanson, “Tunable diode laser absorption sensor for temperature and velocity measurements of O2 in air flows,” in Technical Digest, Twenty-Ninth Aerospace Sciences Meeting (American Institute of Aeronautics and Astronautics, Washington, D.C., 1991), paper 91-0360.

A. C. Stanton, D. S. Bomse, J. A. Silver, “A nonintrusive diagnostic for water vapor in high temperature flow fields,” Tech. Rep. R90-01, for National Aero-Space Plane Joint Program Office AFSC/NAC (Southwest Sciences, Inc., Santa Fe, N.M., 1991).

M. P. Arroyo, R. K. Hanson, “Tunable diode laser absorption technique for detection of water vapor in aerodynamic flows,” in Technical Digest, Thirtieth Aerospace Sciences Meeting (American Institute of Aeronautics and Astronautics, Washington, D.C., 1992) paper 92-0510.

hitran data base, 1992 ed. (Digital Product Section, National Climatic Center, National Oceanic and Atmospheric Administration, Federal Building, Asheville, N. C. 28801).

G. Herzberg, Molecular Spectra and Molecular Structure II. Infrared and Raman Spectra of Polyatomic Molecules (Van Nostrand Reinhold, New York, 1945).

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Figures (16)

Fig. 1
Fig. 1

Line position and strength for the ν1 + ν3 band at 296 and 1500 K.

Fig. 2
Fig. 2

Diode laser spectrum at three injection currents. The spectral linewidth is much larger than the laser linewidth because of instrument broadening.

Fig. 3
Fig. 3

Calculated absorption at T = 294 K, xH2O = 0.0146 (laboratory room air, top panel) and at T = 1720 K, xH2O = 0.158 (methane–air flame, bottom panel) for the spectral region of the diode laser.

Fig. 4
Fig. 4

Tuning capabilities of the diode laser (Tlaser = 20 °C).

Fig. 5
Fig. 5

Experimental schematic for the experiments in a flame.

Fig. 6
Fig. 6

Raw data trace showing absorption scans of the lines 5–6 of H2O in laboratory room air with T = 294 K (Tlaser = 40 °C).

Fig. 7
Fig. 7

Fitting of the peak positions in the étalon signal shown in Fig. 6.

Fig. 8
Fig. 8

Reduced profiles and residuals from the data of Fig. 60 = 7215.534, Δν = 21.6 GHz).

Fig. 9
Fig. 9

Measured strengths for four different spectral lines. The horizontal lines represent the average values for each data set. These values and the wave numbers of the lines are listed in Table 2, together with the symbols used in the figure.

Fig. 10
Fig. 10

Measured self-broadening coefficient for the same lines represented in Fig. 9. The horizontal lines represent the average value for each data set. These values and the wave number of each line are listed in Table 2, together with the symbols used in the figure.

Fig. 11
Fig. 11

Experimental (dots) and calculated (solid curve) normalized profiles for the lines probed in the experiments in room air. Theoretical conditions are as follows: T = 294 K, xH2O = 0.0146, P = 1 atm, L = 108.5 cm.

Fig. 12
Fig. 12

Intensity ratio versus temperature for selected low-temperature line pairs.

Fig. 13
Fig. 13

Sensitivity of intensity ratio to temperature for the low-temperature line pairs of Fig. 12.

Fig. 14
Fig. 14

Measured line intensity versus E″ at room temperature.

Fig. 15
Fig. 15

Experimental (dots) and calculated (solid curve) normalized profiles for the lines probed in the experiment in a methane–air flame. Theoretical conditions are as follows: T = 1720 K, xH2O = 0.158, P = 1 atm, L = 9 cm.

Fig. 16
Fig. 16

Measured line intensity versus E″ at high temperature.

Tables (5)

Tables Icon

Table 1 Spectroscopic Parameters for the Strongest Water Lines between 1383 and 1387 nma

Tables Icon

Table 2 Line Parameters Obtained from Absorption Data Acquired in a 1 5-cm-Long Static Cell at T = 296 K

Tables Icon

Table 3 Line Parameters Obtained from Absorption in a 108.5-cm Path Length in Laboratory Room Air at T = 294 K

Tables Icon

Table 4 Selected Line Pairs for H2O Thermometry at Low Temperatures

Tables Icon

Table 5 Line Parameters Obtained from the Absorption in a 9-cm Path Length in a Fuel Lean (ϕ = 0.82) Methane–Air Flame at T = 1720 Ka

Equations (10)

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

τ ( ν ) = I ( ν ) / I 0 = exp [ - k ( ν ) L ] ,
k ( ν ) = P abs S ( T , ν 0 ) ϕ ( ν - ν 0 ) ,
a = ( ln 2 ) 0.5 γ c / γ d ,
γ d = 3.581 × 10 - 7 ( T / M ) 0.5 ν 0 ,
S ( T , ν 0 ) = S ( T 0 , ν 0 ) ( T 0 / T ) [ Q ( T 0 ) / Q ( T ) ] × [ 1 - exp ( - h c ν 0 / k T ) ] × [ 1 - exp ( - h c ν 0 / k T 0 ) ] - 1 × exp [ - ( h c E / k ) ( 1 / T - 1 / T 0 ) ] ,
Q ( T ) = 0.5 [ ( π / A B C ) ( k T / h c ) 3 ] 0.5 × [ 1 - exp ( - h c ν 1 / k T ) ] - 1 × [ 1 - exp ( - h c ν 2 / k T ) ] - 1 × [ 1 - exp ( - h c ν 3 / k T ) ] - 1 ,
R = S ( T 0 , ν 1 ) / S ( T 0 , ν 2 ) × exp [ - ( h c / k ) ( E 1 - E 2 ) ( 1 / T - 1 / T 0 ) ] .
T = ( h c / 2 k ) ( E 1 - E 2 ) = 0.72 Δ E ,
X = P abs / P .
SMSR = - 10 log ( I s / I m ) ,

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