The authors are with the High Temperature Gasdynamics Laboratory, Department of Mechanical Engineering, Stanford University, Stanford, California 94305-3032.
M. P. Arroyo and R. K. Hanson, "Absorption measurements of water-vapor concentration, temperature, and line-shape parameters using a tunable InGaAsP diode laser," Appl. Opt. 32, 6104-6116 (1993)
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.
Jonathan T. C. Liu, Gregory B. Rieker, Jay B. Jeffries, Mark R. Gruber, Campbell D. Carter, Tarun Mathur, and Ronald K. Hanson Appl. Opt. 44(31) 6701-6711 (2005)
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The parameter a is evaluated for P = 1 atm, at the laboratory room air conditions (T = 294 K) and at the methane–air flame conditions (T = 1720 K). 1 atm = 760 torr.
These lines correspond to the 2ν2 + ν3 band. All the other lines correspond to the 2ν1, + ν3 band.
Table 2
Line Parameters Obtained from Absorption Data Acquired in a 1 5-cm-Long Static Cell at T = 296 K
The parameter a is evaluated for P = 1 atm, at the laboratory room air conditions (T = 294 K) and at the methane–air flame conditions (T = 1720 K). 1 atm = 760 torr.
These lines correspond to the 2ν2 + ν3 band. All the other lines correspond to the 2ν1, + ν3 band.
Table 2
Line Parameters Obtained from Absorption Data Acquired in a 1 5-cm-Long Static Cell at T = 296 K