The Rotational Zeeman Effect of Carbonylselenide, OCSe, its Molecular Electric Quadrupole Moment, and the Effects of the C = Se Stretching and the Bending Vibration; A High Resolution Microwave Fourier Transform Study

The results of a high resolution microwave Fourier transform study of the rotational Zeeman effect in the J' = 2￫J" = l transitions of Se, Se, and Se are reported. From the observed g-values and susceptibility anisotropies, experimental values were derived for the molecular electric quadrupole moment, for the anisotropy in the second moments of the electronic charge distribution, for the paramagnetic susceptibility perpendicular to the OCSe chain, and for the sign of the electric dipole moment. From the Zeeman data observed for the /-type doublet, the paramagnetic susceptibility parallel to the OCSe-axis, which by symmetry is zero for the linear configuration, could be derived as a function of the bending angle, ß. Ab initio calculations of the molecular electric quadrupole moment were carried out. Fair agreement with the experimental value was obtained at the CID/LANLIDZ + pol level of computation. The Lorentz-Stark effect, which usually leads to perturbations in the Zeeman patterns of /-type doublet lines, vanishes if data collection starts with a delay 2 μs after the end of the exciting pulses. This finding is attributed to the short collisional lifetime of fast molecules and suggests new experiments in the field of rotational relaxation studies.