Rotation Vibration and Electronic Relaxation

Abstract

In this paper we present experimental results demonstrating the manifestation of Intramolecular Vibrational energy Redistribution (IVR) on the vibrational energy dependence of the emission quantum yield in anthracene and 9-cyanoanthracene. Strong rotational effects on the fluorescence quantum yields from vibrational states in the S₁ manifold of 9-cyanoanthracene were observed, which serve as the fingerprints of Coriolis coupling, serving as the dominant vibronic coupling mechanism leading to IVR. We discuss the possible manifestation of intratriplet rotational induced IVR in pyrazine as the dominant channel that controls its controversial S₁ excited state dynamics, invoking Vibrational Crossing as a new intra and interstate mixed intramolecular radiationless process. We conclude that rotational effects play a central role in IVR, which can strongly enhance interstate electronic relaxation.