ABSTRACT
A line tunable deuterium fluoride laser was used to measure the pressure dependence of the water vapor continuum absorption at 25 degrees C in the 3.5-4.0-microm spectral region. From measurements of the absorption of 14.3 Torr of deuterium depleted water vapor buffered by several air-broadening pressures, an unexpectedly small foreign-to-self-broadening coefficient of 0.011 with a factor of 2 uncertainty as well as an unusually strong self-contribution for the water vapor continuum absorption were observed. These measurements can be used to infer contributions to the water vapor continuum in the 3-5-microm window from both far wing and aggregate-water-molecule type absorptions.
ABSTRACT
Water vapor absorption coefficients are reported for nine HF laser wavelengths ranging from 3418.1600 cm(-1) to 3788.2253 cm(-1) for temperatures ranging from -18 degrees C to 25 degrees C. Pure water vapor as well as airbroadened (N(2)/O(2)) water vapor absorptions were measured at pressures from less than 1-764 Torr with some of the air-broadened data being used to extract effective self-to-foreign-broadening parameters in the vicinity of the laser frequencies. Limited data were also collected on O(2)-broadened water vapor absorption as well as pure and air-broadened CO(2) absorption. The CO(2) data agree reasonably well with theoretical predictions; but the air- and O(2)-broadened water vapor data show greater absorption than theoretically predicted and seem to imply a super Lorentz/Voigt line shape for H(2)O.
