High sensitivity ICLAS of H218O in the 12,580-13,550 cm-1 transparency window

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High sensitivity ICLAS of H 2 18 O between 13 540 and 14 100 cm -1

International audienceThe high resolution absorption spectrum of 18O enriched water was recorded between 13 540 and 14 100 cm -1 by high sensitivity Intracavity Laser Absorption Spectroscopy (ICLAS). This spectral region corresponds to the relatively strong 4ν polyad. Four isotopologues of water (H 218O, H 216O, H 217O, HD 18O) are found to contribute to the spectrum. About 1800 H 218O lines were assigned by comparison with variational calculations. Altogether, 855 accurate energy levels of H 218O were determined from transitions attributed to 23 upper vibrational states, 342 of them being reported for the first time. New information includes 84 energy levels of H 217O present with a 1.5% relative concentration in the sample and the rotational structure of the 4ν 3 band of HD 18O at 13814.520 cm -1. By comparison with variational calculations and with ICLAS absolute intensity values, a systematic overestimation by about 25% has been evidenced for the H 218O intensity values included in the HITRAN database for the 12 400-14 520 cm -1 range