Application of the indirect dephasing model to resonance and dispersed fluorescence in the isolated molecular complex

Abstract

The theory of indirect dephasing proposed by Hiroike is applied to studying the mechanism of line broadening in resonance and dispersed fluorescence spectra of molecular complexes in supersonic free jet. In the indirect dephasing model, the width of the luorescence spectra which is characterized by the homogeneous linewidth can be expressed in terms of two parameters, the rate of intramolecular vibrational redistribution (IVR), γ and frequency change induced by the IVR, δω. It is shown that the non-Markovian character introduced into the interaction between the intra- and intermolecular modes reduces the indirect dephasing rate. The theory is applied to calculation of the linewidth of the resonance fluorescence of the tetrazine–Ar molecular complex excited in 6a1 vibronic level. The introduction of the non-Markovian character is necessary to calculate the linewidth of the fluorescence in a molecular complex with a few intermolecular modes such as tetrazine–Ar.