S-33 NUCLEAR-QUADRUPOLE COUPLING IN THE MICROWAVE-SPECTRUM OF METHYLTHIOCYANATE

The rotational spectrum of S-33-methylthiocyanate in the vibrational g round state was observed in natural abundance by molecular beam Fourie r transform microwave (MB-FTMW) spectroscopy. We were able to determin e the relational and centrifugal distortion constants, the methyl inte rnal relation parameters, and the N-14 and S-33 quadrupole coupling co nstants. The rotational constants were found to be A = 15 598.104(83)M Hz, B = 4144.5631(3) MHz and C = 3338.1246(2) MHz. For the torsional g round state (A-species) the S-33 nuclear quad rupole coupling constant s were obtained chi(aa) = -40.513(4)MHz, chi(bb) = -7.166(6)MHz and ch i(cc) = 47.679 (7) MHz. The corresponding constants for the E-species lines agree with these values within the given error limits. Additiona lly the rotational and centrifugal distortion constants, the methyl in ternal rotation, and the N-14 quadrupole coupling constants for the S- 32- and S-34-isotopomer could be improved.