Water continuum CO2 laser absorption spectra are reported for temperatures between 27 and −10°C. The continuum is found to possess a negative temperature coefficient. The results obtained suggest that the magnitude of this temperature coefficient increases with increasing water pressure and decreasing temperature. The temperature coefficients between 27 and 10°C for air mixtures containing 3.0- and 7.5-Torr water vapor are −2.0 ± 0.4 and −2.9 ± 0.5%/°C, respectively. For mixtures with 3.0-Torr water the 10–0°C temperature coefficient is −7.7 ± 0.2%/°C. The temperature and water pressure dependencies observed for the continuum suggest that while both collisional broadening and water dimer mechanisms contribute to the continuum, the dimer mechanism is more important over this temperature range.
© 1983 Optical Society of America
Original Manuscript: July 25, 1983
Published: December 1, 1983
Gary L. Loper, Maureen A. O'Neill, and Jerry A. Gelbwachs, "Water-vapor continuum CO2 laser absorption spectra between 27°C and −10°C," Appl. Opt. 22, 3701-3710 (1983)