The Ï 1 fundamental bands of trans- and cis-DONO studied by high-resolution Fourier-transform spectroscopy

The absorption spectrum of deuterated nitrous acid DONO in the region from 2350 to 3000 cm−1 has been recorded at a resolution of 0.003 cm−1 using a Fourier-transform spectrometer. For the first time, 1366 a- and b-type transitions in the υ1 fundamental band of trans-DONO and 741 b-type transitions in the υ1 fundamental band of cis-DONO have been assigned. Rotational and centrifugal distortion constants up to sextic order were determined for the v1 = 1 states of trans- and cis-DONO using non-linear least-squares calculations. Synthetic spectra calculated using the new rovibrational constants obtained for both species reproduce the observed spectra very well. In addition, the infrared transitions of this study were used, together with previously published pure rotational transitions, to determine improved rotational and centrifugal distortion constants of the ground states of trans- and cis-DONO.