Below Room Temperature Measurements Of The 8-12 μ M Water Vapor Continuum Absorption

The CO2 laser photoacoustic technique has been used to measure 002 laser absorption spectra of water vapor/air mixtures containing various water vapor partial pressures at selected temperatures down to 10°C. At CO2 laser wavelengths where water vapor continuum absorption contributions are dominant, the water absorp-tion possesses a temperature coefficient of -2.2%/°C between 27°C and 10°C. At the fixed temperatures em-ployed, the water continuum possesses a dependence on water vapor partial pressure that includes both linear and quadratic terms. A similar temperature coefficient and water partial pressure dependence has been observed in previous studies of water continuum absorption between room temperature and 100°C.