Cavity ring down spectroscopy of 17O enriched water vapor near 1.73 µm

Abstract

The room temperature absorption spectrum of water vapour highly enriched in 17O is recorded by cavity ring down spectroscopy (CRDS) near 1.73 µm. Two series of recordings were performed with pressure values of about 0.12 and 8.5 Torr from 5693 to 5850 cm−1. The noise equivalent absorption (αmin) of the spectra is better than 10−10 cm−1 allowing for the measurements of water lines with intensity down to 10−29 cm/molecule. A total of 1132 lines were assigned to 1220 transitions of five water isotopologues (H216O, H217O, H218O, HD16O, and HD17O). Their intensities span near five orders of magnitude from 10−29 to 10−24 cm/molecule at 296 K. The assignments were performed using known experimental energy levels as well as calculated line lists based on the results of Schwenke and Partridge.Most of the new results concern the H217O isotopologue: 483 transitions were measured while only the 27 strongest were previously known. Overall 104 levels were newly determined for H217O (64 levels), H218O (16), HD17O (23) and HD16O (1) and a few additional levels were corrected compared to the literature. The obtained results are compared to the water line list in the HITRAN2016 database, to the ExoMol energy levels and to the empirical energy levels recommended by an IUPAC task group.