Diode laser spectroscopy of H216O spectra broadened by N2 and He in 1.39 µm region

Abstract

Experimental spectra of pure water vapor and its mixtures with N2 and He were measured in a pressure range (4–19 for pure H2O and 70–630mBar for H2O diluted in N2 and Ne) by the diode laser spectrometer between 7184 and 7186cm−1. The noise equivalent absorption cross-section of the all observed spectra varied from 1.2 to 4.3×10–24cm2/molec allowing signal to noise ratio from 10 for weak (intensity on the order of 5×10–25cm/molec at 296K) to 15,000 for strong (intensity on the order of 6×10–22cm/molec) spectral lines respectively. The Voigt, Galatry, and Speed-dependent Voigt (SDV) profiles were used to fit the experimental spectra. This region includes 7 absorption lines of H2O and one HDO line according to the new line lists of H2O. Line positions, intensities, line shift, collisional broadening and narrowing coefficients for 6 spectral lines were retrieved by multispectrum fitting procedure assuming the linear pressure dependence. The spectral parameters of the doublet (ν1+ν3; 660←661; 661←660) at 7185.596cm−1 were determined for the first time.