title: Density matrix analysis, simulation, and measurements of electronic absorption and fluorescence spectra of spirobifluorenes.
abstract: The linear absorption and fluorescence spectra as well as the oscillator strengths of 2,2',7,7'-tetraphenyl-9,9'-spirobifluorene (A), 2,2',7,7'-tetrakis(biphenyl-4-yl)-9,9'-spirobifluorene (B), and 2,2',7,7'-tetrakis(9,9'-spirobifluoren-2-yl)-9,9'-spirobifluorene (C) are calculated on the basis of the collective electronic oscillator (CEO) approach of Mukamel et al. (see, e.g., Chem. Rev. 2002, 102, 3171). The graphical visualization and quantitative characterization of CEO modes allows one to extract the real-space distribution of electronic excitations of the molecules under study. Effects of the lengthening and branching of the oligophenylene segments have been analyzed. The influence of the lowest excited (S1) vs ground-state (S0) geometry changes on the CEO modes is investigated and related to the geometry changes of the molecular parts. The obtained theoretical results are in good agreement with experimental trends observed in absorption and fluorescence data.
authors.affiliation: Department of Chemical Physics, Slovak University of Technology, Radlinského 9 SK-812 37 Bratislava, Slovakia. vladimir.lukes@stuba.sk
authors.forename: Vladimir
authors.initials: V
authors.lastname: Lukes
authors.forename: Tibor
authors.initials: T
authors.lastname: Pálszegi
authors.forename: Franz
authors.initials: F
authors.lastname: Milota
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Sperling
authors.forename: Harald Friedrich
authors.initials: HF
authors.lastname: Kauffmann