Pressure broadening and shift coefficients of H₂O due to perturbation by N₂, O₂, H₂and He in the 1.39 μm region: experiment and calculations

Abstract

Near-infrared diode laser spectrometry was used to determine the pressure broadening and shift effect on H2O due to N2, O2, H2 and He in the 1.39 µm region. Halfwidths and shifts of water vapour were measured for six transitions. These lines are from the ν 1+ν 3 and 2ν 1 bands. A complete set of H2O transitions with various J values was investigated, including the lines selected to monitor in situ stratospheric H2O with the SDLA, a balloon-borne diode laser spectrometer. Experimental results are compared with theoretical calculations based on a semi-empiric technique that incorporates various corrections to the Anderson theory. This approach is performed in the framework of the impact approximation, which makes interpretation of the collision process simpler and allows reliable results to be obtained.