Herzberg‐Teller Interaction and Vibronic Coupling in Molecular Crystals I. The Simple Model

Abstract The vibronic absorption spectrum of a molecular crystal, corresponding to the formation of an exciton in a state forbidden by the intramolecular symmetry, is investigated. It is assumed that intensity is borrowed from a higher electronic state with help of the Herzberg‐Teller mechanism. Non‐totally and totally symmetric intramolecular vibrations are included into this consideration. Formulae for relative intensities of different vibronic lines in the spectrum are obtained. The one‐ and two‐phonon regions of the spectrum are discussed.