Microwave Spectroscopy of Planar and Quasi-planar Organic Molecules: Indole and 1,2,3,4-tetrahydroquinoline

Abstract In this study, 3179 and 3813 rotational transition frequencies for indole and 1,2,3,4-tetrahydroquinoline, respectively, were analyzed using the PGOPHER software. In both analyses, all the matrix elements of the sextic rotational Hamiltonians were fitted simultaneously to the hyperfine quadrupole terms. The global fits of all the transition frequencies provided the most precise ground state molecular parameters for both molecules, so far. The presented experimental results are in concordance with the density functional theory calculations.