title: Enhanced Davydov Splitting in Crystals of a Perylene Diimide Derivative.
abstract: We report the polarized absorption spectra of high-quality, thin crystals of a perylene diimide (PDI) species with branched side chains (B2). The absorption spectrum shows exemplary polarization-dependent H-like and J-like aggregate behavior upon orthogonal excitation, with a sizable Davydov splitting (DS) of 1230 cm-1and peak to peak splitting of 3040 cm-1. The experimental results are compared to theoretical calculations with remarkable agreement. The theoretical analysis of the polarized absorption spectra shows evidence of a high degree of intermolecular charge transfer, which, along with Coulombic coupling, conspires to create the unprecedented DS for this family of dye molecules. The large polarization dependence of the electronic spectra is attributed to the unique twisted crystal structure, in which a substantial rotational displacement exists between neighboring chromophores within a π-stack. These results highlight the strong sensitivity of the Davydov splitting to intermolecular geometry in PDI systems.
authors.affiliation: Department of Chemistry, Lafayette College , Easton, Pennsylvania 18042, United States.
authors.forename: Ashli
authors.initials: A
authors.lastname: Austin
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Hestand
authors.forename: Ian G
authors.initials: IG
authors.lastname: McKendry
authors.forename: Chuwei
authors.initials: C
authors.lastname: Zhong
authors.affiliation: Department of Chemistry, Lafayette College , Easton, Pennsylvania 18042, United States.
authors.forename: Xuanyu
authors.initials: X
authors.lastname: Zhu
authors.forename: Michael J
authors.identifier: http://orcid.org/0000-0003-0212-2557
authors.initials: MJ
authors.lastname: Zdilla
authors.forename: Frank C
authors.identifier: http://orcid.org/0000-0003-3044-6727
authors.initials: FC
authors.lastname: Spano
authors.affiliation: Department of Chemistry, Lafayette College , Easton, Pennsylvania 18042, United States.
authors.forename: Jodi M
authors.identifier: http://orcid.org/0000-0002-2181-9408
authors.initials: JM
authors.lastname: Szarko