title: Spectral diffusion of single molecules in a hierarchical energy landscape.
abstract: Spectral diffusion as a result of both the transitions between different molecular conformers and the ''molecular softness'' of quasi-free perylene diimides on a SiO(2) surface is investigated by means of single-molecule spectroscopy, which reveals the time dependence of both the fluorescence spectra and the three-dimensional orientation. Spectral wavelengths of all single emitters cover a wide energy range of about 0.27 eV, which is due to different types of conformers with large differences in optical transition energy. Time-dependent spectral trajectories of single emitters within this wavelength manifold are evaluated with a model transcribed from the analysis of spatial diffusion. Spectral diffusion processes are closely correlated with fluorescence emission and excitation power. The overall analysis of spectral diffusion reveals, similar to proteins, a hierarchy of energy barriers in a broad energy landscape.
authors.affiliation: Institute of Physics and nanoMA, Chemnitz University of Technology, 09107 Chemnitz, Germany. stefan.krause@physik.tu-chemnitz.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Krause
authors.forename: Danny
authors.initials: D
authors.lastname: Kowerko
authors.forename: Richard
authors.initials: R
authors.lastname: Börner
authors.forename: Christian G
authors.initials: CG
authors.lastname: Hübner
authors.forename: Christian
authors.initials: C
authors.lastname: von Borczyskowski