Asymmetric rotor analysis of DSOD spectra up to the rQ3 branch near 653Â GHz

We report the unequivocal identification of the rQ3 branch of perdeutero oxadisulfane, DSOD, which has been produced in a discharge of D2S together with D2O. By employing the Cologne Terahertz Spectrometer, we have located the band center near 653 GHz, in very close agreement with earlier results deduced from the rQ0 and rQ2 branches. The A0, B0, and C0 rotational constants have been determined by carrying out an asymmetric rotor least squares fit with all presently available data, including new R- and P-branch lines. Both, b- and c-type transitions have been observed and the relative dipole moment μc/μb has been determined from relative line strengths. All results agree very well with quantum chemically calculated values.