PULSED-BEAM MICROWAVE FOURIER-TRANSFORM MEASUREMENTS ON ISOTOPICALLY SUBSTITUTED VAN-DER-WAALS DIMER NE-OCS

Pure rotational spectra of seven isotopomers of Ne-OCS (Ne-OCS, Ne-22-OCS, Ne-21-OCS, Ne-(OCS)-O-18, Ne-(OCS)-C-13, Ne-(OCS)-S-34, and Ne-(OCS)-S-33) have been investigated using a pulsed jet cavity microwave Fourier transform spectrometer. Rotational and centrifugal distortion constants have been determined for all species, as well as the nuclear quadrupole coupling constants of S-33 and Ne-21 in Ne-(OCS)-S-33 and Ne-21-OCS, respectively. Harmonic force field analyses have been performed which account for the Variations in the distortion constants between the isotopomers. Effective and ground state average structures have been obtained and are discussed in light of the nuclear quadrupole coupling constants and of dipole moment measurements. The determined coupling constants have provided a means of comparing the effects of perturbation of the electronic structures of both constituents upon complexation. An electrostatic model has been applied to calculate the Ne-21 coupling constants and a possible source of their disagreement with experiment is discussed. (C) 1995 Academic Press, Inc.