PRECISE MEASUREMENTS OF PRESSURE BROADENING AND SHIFT FOR SEVERAL H2O LINES IN THE NU-2 BAND BY ARGON, NITROGEN, OXYGEN, AND AIR

Foreign gas effects by Ar, N2, O2, and air (broadening and frequency shifts) of several rovibrational lines of H2O in the ν2 band were measured precisely by using a stabilized diode laser spectrometer. The additive behavior of the line-broadening parameters is supported by separate measurements with air, oxygen, and nitrogen as foreign gases: the pressure broadening due to air can be calculated from the weighted mean of the measured N2 and O2 coefficients. In contrast, the line shifts are found not to be additive although they respond linearly to pressure increase in the case of a single foreign gas. The line broadening with Ar was found to be much smaller than for N2 or O2. Collisional narrowing phenomena were clearly observed for some of the high-J H2O lines. Line shifts due to Ar are found to be as large as those due to N2 or O2. © 1992.