THE FAR-INFRARED FOURIER-TRANSFORM SPECTRUM OF H2SE

In the present work, we study the spectrum of the H2Se molecule in the far-infrared region. This work is a continuation of our experimental investigation of the anomalous "fourfold clustering effect" exhibited by the rotational energy levels in the vibrational ground state of H2Se. The spectrum in the region 30-360 cm-1 was measured with a Bruker IFS 120 HR interferometer attached to a 3-m-long cell. In order to observe transitions involving high J and Ka quantum numbers the cell was heated to 90°C. About 2500 lines were identified and fitted using a modified Watson Hamiltonian. Improved sets of rotational and centrifugal distortion constants for all six selenium isotopomers were obtained. It is shown that the fourfold clustering of rotational levels, as well as the observed linestrength distortions, can be explained in terms of localized wavefunctions. © 1993 Academic Press, Inc.