Coriolis interaction of small and large aromatic hydrocarbons

Abstract

Energy shifts by Coriolis interaction between the degenerate levels are discussed for aromatic hydrocarbons with D6h symmetry, benzene and coronene. The degenerate vibrations of e symmetry (the second-order irreducible representation) necessarily exist in a molecule with the n-fold symmetry axis (n⩾3), of which the rotational levels are expressed by the oblate symmetric-top model. The high-resolution spectrum was accurately analyzed by applying the theoretical model of Coriolis interaction, which significantly shifts the vibrational and rotational levels. The Coriolis interaction enhances intramolecular vibrational energy redistribution (IVR) at high vibrational levels in the electronic excited state. A rapid decrease in the fluorescence quantum yield at the vibrational levels above 3000 cm−1 in the S1 state of benzene (Channel 3) is shown to be mainly due to level mixing by Coriolis interaction.