NUCLEAR-QUADRUPOLE HYPERFINE-STRUCTURE IN THE ROTATIONAL AQ1-SUBBRANCH OF DEUTEROISOTHIOCYANIC ACID, DNCS

The two-nuclei quadrupole hyperfine structure of four (a)Q1-subbranch transitions of deuteroisothiocyanic acid, DNCS, has been resolved and analyzed by use of a waveguide microwave Fourier transform spectrometer. The analysis yielded one previously unknown quadrupole coupling constant (chi- = chi(bb) - chi(cc)) for both nitrogen (chi--N = +27.6(11) kHz) and deuterium chi--D = +175.8(11) kHz). Taking into account the results from earlier work on HNCS, DNCS, HNCO, and DNCO, the orientations of the principal axis systems of the two quadrupole coupling tensors could be calculated. It appears that while the deuterium tensor is aligned to the D-N internuclear axis as expected, the nitrogen tensor is tilted away from the bisector of the DNC angle by 13-degrees towards the NCS chain.