Shock-tube study of high-pressure H2O spectroscopy

Water-vapor absorption features near 7117 7185, and 7462 cm(-1) were probed at pressures to 65 atm (1 atm = 760 Torr) and temperatures to 1800 K in sh ock-heated mixtures of H2O in N-2 and Ar with a diode-laser source. Calcula ted absorbances based on Voigt line shapes and measured line parameters wer e in good agreement, within 10%, with measured absorbances at 7185.4 and 71 17.4 cm(-1). We obtained temperature-dependent N-2 and Ar shift parameters for H2O absorption features by shifting the calculated spectra to match the recorded absorption scan. Absorbance simulations based on line parameters from HITRAN and HITEMP were found to be similar over the range of temperatu res 600-1800 K and were within 25% of the measurements. The combined use of Toth's [Appl. Opt. 36, 4851 (1994)] line positions and strengths and HITRA N broadening parameters resulted in calculated absorption coefficients that were within 15% of the measurements at all three probed wavelengths. (C) 1 999 optical Society of America OCIS codes: 120.1740, 300.1030, 300.6260, 30 0.0300; 010.7340, 130.6010.