Some Spectral Emissivities of Water Vapor in the 27-μ Region*

Spectral emissivities of water vapor were measured in the 2.7-μ region, at temperatures up to 1273°K. The measurements were used to calculate spectral and integrated infrared radiance of hot water vapor for several cases of interest. The spectrum of hot H2O is relatively poor in strong “hot” bands, in contrast to the case of CO2. The general character of the rotational structure in the spectrum of the hot gas is similar to the case of room temperature, although some additional lines are observed at high temperatures. Consequently, care must be taken in selecting the spectral intervals over which radiance integrals are to be calculated.