Vibrational potential energy surfaces for phthalan and 1,3-benzodioxole in their S-0 and S-1 (pi,pi*) states Conference Paper uri icon

abstract

  • The far-infrared, Raman and ultraviolet spectra of phthalan and 1,3- benzodioxole were recorded and analyzed. In addition, the fluorescence excitation spectra and the dispersed fluorescence spectra of the jet-cooled molecules were also investigated. The far-infrared spectrum of phthalan shows single, double, and triple quantum jump transitions between the various ring- puckering energy levels. Many hot bands involving the ring-puckering and ring-flapping vibrations were also observed. The ring-puckering energy level spacings possess an irregular pattern and calculations show this to arise from the kinetic energy interactions between the puckering and flapping vibrations. A two-dimensional potential energy surface, which nicely fits all the observed data, was determined. This has a barrier to planarity of 35 cm-1. Dispersed fluorescence spectra of jet-cooled phthalan molecules helped to confirm the far-infrared assignments, and the fluorescence excitation spectra were recorded to determine the vibrational energy levels from the puckering in the S1(,*) electronic excited state. Ultraviolet absorption spectra were used to better understand the excited state energy levels. The far- infrared spectra of 1,3-benzodioxole were also reanalyzed. Because of the anomeric effect, 1,3-benzodioxole is puckered with a barrier to planarity of 125 cm-1. Analysis of the ultraviolet absorption spectra and the fluorescence excitation spectra of the jet-cooled molecules is also in progress and shows that the barrier increases in the S1(,*) state.

published proceedings

  • JOURNAL OF MOLECULAR STRUCTURE

author list (cited authors)

  • Laane, J., Sakurai, S., Klots, T., Meinander, N., Morris, K., Chiang, W. Y., & Bondoc, E.

citation count

  • 2

complete list of authors

  • Laane, J||Sakurai, S||Klots, T||Meinander, N||Morris, K||Chiang, WY||Bondoc, E

publication date

  • May 1999