The first hexad {(040), (120), (021), (200), (101), (002)} of H₂¹⁸O: experimental energy levels and line intensities

Abstract

The spectrum of 18 O-enriched water vapor has been recorded between 5900 and 8000 cm −1 , with the aid of a Fourier-transform spectrometer. Its analysis allowed the determination of 437 accurate rotational levels belonging to the hexad of interacting states {(040), (120), (021), (200), (101), (002)}of H 2 18 O. Among these vibrational states, the (040), (120), and (002) ones had never been observed before. Moreover, 726 line intensities belonging to the 4ν 2 , ν 1 + 2ν 2 , 2ν 2 + ν 3 , 2ν 1 , ν 1 + ν 3 , and 2ν 3 bands have been measured with an uncertainty of 6%.