| Popis: |
High-resolution Fourier-transform rotational spectroscopy, combined with supersonic molecular beams, is an invaluable tool for studies of large amplitude motions in molecular systems, especially internal rotation tunneling of methyl groups. Methyl rotors are highly sensitive to local/non-local electronic environment and steric interactions. Therefore a systematic rotational-spectroscopic investigation of methyl rotors, along with the theoretical quantum chemical calculations, may reveal useful structural information of molecules and their weakly bonded van der Waals complexes. The dissertation includes rotational spectroscopic investigations of four sets of molecular systems: 1-7 methylindoles, conformers and argon complex of 2-phenylethyl methyl ether (2PME), normal/isotopologues and argon complex of guaiacol (2-methoxyphenol), and three structurally-isomeric methylstyrenes. Rotational spectra were recorded in the 10.5 – 22 GHz frequency range and transition frequencies were assigned to a suitable Hamiltonian, to determine the lowest energy structures, three-fold potential energy barriers to methyl internal rotation, and nitrogen-14 nuclear quadrupole coupling constants, where applicable. |
