FAR-INFRARED, ULTRAVIOLET, AND FLUORESCENCE SPECTRA AND VIBRATIONAL POTENTIAL ENERGY SURFACES OF PHTHALAN AND 1,3-BENZODIOXOLE IN THEIR GROUND AND EXCITED STATES

Author Institution: Department of Chemistry, Texas A\&M University; BDM Oklahoma, BartlesvilleThe far-infrared spectra of phthalan and 1,3-benzodioxole in the 30 to $300 cm^{-1}$ region show numerous transitions of the ring-puckering $(\Delta v_{p} = 1, 2$, and 3) and ring-flapping vibrations. Detailed energy maps for the vibrational states have been obtained and used to determine two-dimensional potential energy surfaces for the electronic ground states. A one-dimensional ring-puckering potential energy function for phthalan, however, can not adequately fit the irregular ring-puckering sequence. The two-dimensional calculations show that the spectral irregularities arise primarily from kinetic energy interactions. Phthalan has a small barrier to planarity of $35 cm^{-1}$ while that of 1,3-benzodioxole is considerable larger due to the anomeric effec