Pyrrole and furan, two aromatic five-membered ring molecules, have been the subject of extensive ab initio and experimental studies. We have taken Fourier transform far-infrared spectra of these molecules at the Canadian Light Source. Two fully-entangled vibrational bands of furan, n8 and n21 at ~ 870 and 873 cm-1, that are present in the spectra show some perturbations and interact with each other via Coriolis coupling. In pyrrole, a weak c-type band, n13 at ~ 830 cm-1, is observed, in addition to two other vibrational modes of pyrrole, n9 and n10 at ~ 880 and 864 cm-1, that experience the same perturbation as do the bands of furan. We will discuss our analysis and attempts at deperturbation of these bands.
A larger related molecular system, Catechol, consists of a six-membered ring and two OH groups. The high-resolution rotation-vibration spectra of this molecule have never been taken. However, low-resolution data show some vibrational transitions between ~ 450-4000 cm-1. Motivated by the potential applications of ring molecules in the field of molecular electronics, we decided to take high resolution spectra of Catechol at the Canadian Light source in Saskatchewan. Our progress in obtaining rotationally resolved vibrational spectra of Catechol will also be discussed.