The Rotational Zeeman Effect in Van Der Waals Molecules

209 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.The rotational Zeeman effect in several weakly bound bimolecular complexes, or van der Waals molecules, is examined. The recently developed pulsed Fourier transform microwave spectrometer employing an evacuated Fabry-Perot cavity located inside the bore of a superconducting solenoid is discussed. The zero field rotational spectrum of small hydrocarbon molecules with HX(X = F, Cl, CN) is analyzed and along with the Zeeman effect provides new kinds of information regarding the structure, potential surface, and charge rearrangements in weakly bound complexes.Chapter I gives the motivation for studying the rotational Zeeman effect in weakly bound molecules. The pulsed Fourier transform microwave technique and the adaption of the current Fourier transform microwave spectrometer for Zeeman experiments are described.In Chapter II the results of zero field microwave measurements on acetylene-HF, benzene-HCl, and ethylene-HCN are presented. Analytical methods, including Hamiltonian matrix elements, structural determination, and calculation of well depths and stretching force constants, are discussed for rod-body molecules. The structures, force constants, and internal dynamics are determined for acetylene-HF, benzene-HCl, and ethylene-HCN and are compared to results for similar complexes.Chapter III discusses the rotational Zeeman effect in rare gas-hydrogen halides. The methods for analyzing the rotational Zeeman spectra, including the comparison between the semi-rigid and the full-dynamical models, are presented. The rotational magnetic moment in rare gas-hydrogen halides provides a measure of the Coriolis coupling between the angular momentum of the hydrogen halide and the total angular momentum of the complex and yields information on the angular anisotropy in the potential surface.In Chapter IV, the rotational Zeeman effect in OCHF, OCHCl, and N(,2)HF is presented. The rotational Zeeman parameters of these more strongly bound molecules can be described by the semi-rigid model. The vibrationally averaged structure of these complexes and the dipole moment of N(,2)HF is determined to properly account for these effects in the measured Zeeman parameters. The molecular quadrupole moment enhancement in the complexes is less than that of the molecular dipole moment.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD