ROTATIONAL SPECTROSCOPY OF WEAKLY-BOUND COMPLEXES UTILIZING A HIGH-TEMPERATURE MOLECULAR SOURCE (MICROWAVE)

Rotational spectroscopic studies of several weakly-bound molecular complexes are presented here. These studies were performed using a pulsed Fourier-transform microwave spectrometer, employing a Fabry-Perot cavity and a pulsed, supersonic nozzle. A high-temperature molecular source that permits the study of complexes involving low-vapor-pressure species is presented.;In Chapter II, the rotational Zeeman effect upon several weakly-bound complexes is described. The linear complexes OCO-HF, OCO-DF, OCO-HCl, and SCO-HF are studied. The asymmetric-top complex ArOCS is then discussed, including an analysis of centrifugal distortion and the molecular force field. Molecular g-values, magnetic susceptibility anisotropies, and quadrupole moments are determined for all of the above species.;In Chapter III, the heated-nozzle system is described in detail. It is then used in the study of complexes involving the metallic element mercury. The structure and properties of HgHCl are presented and compared with those of rare gas-hydrogen halide complexes. Force constants and normal frequencies of vibration are also calculated. The HCNHg complex is also studied. It is found that mercury behaves as a Lewis base--as rare gases do--in HgHCl, but as a Lewis acid in HCNHg. The ('201)Hg quadrupole coupling constants in both complexes are then analyzed, resulting in the first experimental estimate of the Sternheimer shielding constant for the mercury atom. Finally, other projects of interest for the heated nozzle system are proposed.;Chapter I presents studies of four weakly-bound species using the original spectrometer developed by Balle and Flygare. The spectroscopic constants and molecular structures of ethylene-HF, furan-HCl, argon-carbonyl fluoride, and propyne-HF are determined. A detailed force-field analysis is given for argon-carbonyl fluoride, a complex which exhibits unusually high "accidental" symmetry. Propyne-HF is the first hydrogen-bound complex to exhibit splittings due to hindered internal rotation caused by the presence of the binding partner.