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High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy
Published on: June 28, 2016
Dimers of quadrupolar chromophores in solution: electrostatic interactions and optical spectra
Cristina Sissa1, Francesca Terenziani, Anna Painelli
1Dip. Chimica GIAF, Università di Parma & INSTM UdR Parma, Parco Area delle Scienze 17/A, 43100 Parma, Italy.
Abstract:
Two dimers of a heteroaromatic quadrupolar (acceptor-donor-acceptor) chromophore have been synthesized with different interchromophoric distances. Optical spectra of dimers in solution show a red shift of the linear absorption band upon decreasing the interchromophore distance, while fluorescence and two-photon absorption spectra are only marginally affected by the interactions. A bottom up approach is adopted to describe the spectra: via a detailed spectroscopic analysis of the monomeric species in solution, we define an essential-state model for the isolated chromophore and use this information to set up a model for the dimers also accounting for interchromophore electrostatic interactions. To discriminate between static screening governed by the static dielectric constant and dynamical screening at optical frequencies, we first solve the problem in the mean-field approximation and then define the excitonic Hamiltonian on the resulting best excitonic basis. Along this line, the evolution of spectral properties with the interchromophore distance is properly rationalized.
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