A study of water vapor absoprtion at CO₂ laser frequencies using a differential spectrophone and white cell /

Abstract : Water vapor absorption at CO2 laser frequencies has been studied using a differential spectrophone and a long path multiple traversal cell. The results of these measurements have been analyzed in terms of the Lorentz line shape and the far wing model for continuum absorption in the 9-10 micrometers wavelength region. An electronically stabilized, grating tunable cw CO2 laser with a nominal output power of 2 watts was used in performing measurements of water vapor absorption as a function of both pressure and temperature. Pressure broadened studies of H2O in N2 at a total pressure of 1 atm. were performed at 27 CO2 laser lines in the 9.4 and 10.4 micrometers bands. A technique for pure (low pressure) H2O measurements using the spectrophone is presented together with some preliminary results at the 10.6 micrometers P(20) laser line. White cell measurements of pure water vapor were performed at seven laser lines in the 9.4 and 10.4 micrometers bands; these data also indicate a significant negative temperature dependence for continuum absorption.