ICLAS of water in the 770 nm transparency window (12 746-13 558 cm−1). Comparison with current experimental and calculated databases

The absorption spectrum of water vapor has been investigated by intracavity laser spectroscopy (ICLAS) in the 12 746-13 558 cm−1 spectral region corresponding to an interesting transparency window of the atmosphere, partly obscured by the A band of molecular oxygen.The achieved sensitivity-in the order of αmin∼10−9 cm−1-has allowed one to measure 1062 water lines with intensities ranging from 1.6×10−28 to 2.35×10−24 cm/molecule at 296 K. A total of 169 new and improved energy levels belonging to 21 vibrational states could be determined from 374 newly measured transitions. The retrieved experimental line list is compared with the spectra calculated by Schwenke and Partridge, and Barber and Tennyson. Comparison with the available experimental databases shows that the obtained results represent a significant improvement of the knowledge of the water absorption in the considered region, in particular in the region of the oxygen A band.