15min:

YU. I. BARANOV, Institute of Experimental Meteorology, Lenina 82, Obninsk, Kaluga region 249020, Russia; P. CHELIN, J. ORPHAL AND L. H. COUDERT, LISA, CNRS/Universités Paris 12 et 7, 61 Avenue du Général de Gaulle, 94010 Créteil, France.

Spectra of an H₂¹⁸O enriched sample of water vapor were recorded from 1780 to 4500~cm^-1, at room temperature, with a Bruker IFS-125 instrument and a liquid nitrogen cooled InSb detector. A single path, 24~cm long, glass cell with ZnSe windows was filled with H₂¹⁸O water vapor at 97.1% purity from CDN Isotopes. For the various spectra, pressures ranging from 4.3 to 18.4~Torr were measured with two different MKS Baratron gauges having 10 and 100~Torr pressure limits. The unapodized spectral resolution was 0.002~cm^-1.

Line strengths were retrieved from these spectra for transitions belonging to the ₂ band with the help of a computer program determining simultaneously line positions, strengths, and linewidths by nonlinear least-squares fitting. The new line strength values were analyzed with those already available for rotational transitions within the ground vibrational state and for ₂ band transitions. In order to account for the anomalous centrifugal distortion displayed by water, this line intensity analysis was performed using the Bending-Rotation Hamiltonian approach.