2003/10/23 by M. Bednarz, J. Knoester, V. A. Malyshev +1
Chemistry · Engineering · Physics and Astronomy · #Molecular Junctions and Nanostructures #Photochemistry and Electron Transfer Studies #Spectroscopy and Quantum Chemical Studies #cond-mat.dis-nn #cond-mat.mtrl-sci
paper · pdf · doi:10.1063/1.1643720
published as J. Chem. Phys. 120, 3827 (2004) · 15 pages, 8 figures
arxiv created 2003/10/23 · openalex publication_date 2004/02/18 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We calculate the temperature dependence of the fluorescence Stokes shift and the fluorescence decay time in linear Frenkel exciton systems resulting from the thermal redistribution of exciton population over the band states. The following factors, relevant to common experimental conditions, are accounted for in our kinetic model: (weak) localization of the exciton states by static disorder, coupling of the localized excitons to vibrations in the host medium, a possible nonequilibrium of the subsystem of localized Frenkel excitons on the time scale of the emission process, and different excitation conditions (resonant or nonresonant). A Pauli master equation, with microscopically calculated transition rates, is used to describe the redistribution of the exciton population over the manifold of localized exciton states. We find a counterintuitive nonmonotonic temperature dependence of the Stokes shift. In addition, we show that depending on experimental conditions, the observed fluorescence decay time may be determined by vibration-induced intraband relaxation, rather than radiative relaxation to the ground state. The model considered has relevance to a wide variety of materials, such as linear molecular aggregates, conjugated polymers, and polysilanes.