Excited-State Structure Modifications Due to Molecular Substituents and Exciton Scattering in Conjugated Molecules.
Attachment of chemical substituents (such as polar moieties) constitutes an efficient and convenient way to modify physical and chemical properties of conjugated polymers and oligomers. Associated modifications in the molecular electronic states can be comprehensively described by examining scattering of excitons in the polymer's backbone at the scattering center representing the chemical substituent. Here, we implement effective tight-binding models as a tool to examine the analytical properties of the exciton scattering matrices in semi-infinite polymer chains with substitutions. We demonstrate that chemical interactions between the substitution and attached polymer are adequately described by the analytical properties of the scattering matrices. In particular, resonant and bound electronic excitations are expressed via the positions of zeros and poles of the scattering amplitude, analytically continued to complex values of exciton quasi-momenta. We exemplify the formulated concepts by analyzing excited states in conjugated phenylacetylenes substituted by perylene.
Hao
H
Li
‡Department of Mathematics, Wayne State University, 656 West Kirby, Detroit, Michigan 48202, United States.
Michael J
MJ
Catanzaro
Sergei
S
Tretiak
⊥Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States.
Vladimir Y
VY
Chernyak
ES approach; bound state; conjugation; electronic excitation; perylene; resonant state; tight-binding model