Lineshape study of argon broadened water vapour overtone transitions in the 818-834Â nm wavelength region

Argon-broadened lineshape parameters of the water vapour rovibrational transitions belonging to the (2 1 1) ← (0 0 0) overtone band in the 818-834 nm wavelength region are measured by using a diode laser spectrometer. The first derivative signals of the overtone transitions have been recorded at different pressures of the perturber keeping the sample at its saturated vapour pressure at room temperature. Use of a balanced detector improves the S/N ratio of the spectra. The recorded lineshapes are fitted with standard Voigt line profiles in order to determine the linestrength and collisional broadening coefficient of 12 water vapour transitions.