Intensity Patterns in Absorption and Fluorescence Spectra of Molecular Dimers: A Comparison between the Vibronic and the Born–Oppenheimer Approach

Abstract

On the molecular theory of aqueous electrolyte solutions. III. A comparison between Born-Oppenheimer and McMillan-Mayer levels of descriptionAfter showing in a previous paper that the Born-oppenheimer zeroth-order approximation can produce accurately the vibronic energies of a model of an excited molecular dimer for a wide range of parameters, the same approach is now used to calculate the vibrational patterns in absorption and fluorescence spectra. Two different levels of approximation depending on the degree of adiabaticity of the electronic wavefunctions are compared with the vibronic treatment. The progressions in the spectra are interpreted in terms of Franck-Condon factors, vibrational borrowing, and vibronic coupling between Born-oppenheimer product wavefunctions.

Influence of energy transfer on the intensity pattern of vibronic excitation studied by reduced density-matrix theory

“…Under a few assumptions, they could derive exact expressions of the line shapes of the vibronic bands associated with the single mode. In their study, the vibration mode mediates the coupling between two electronic states and induces so called the vibronic intensity borrowing [35][36][37][38]. The same model for a molecular dimer with a single vibrational mode was studied by Friesner and Silbey using an analytic approximation method [39].…”