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Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
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Nonradiative excitation energy transport in one-component disordered systems
P Bojarski1, L Kulak, C Bojarski
1Institute of Experimental Physics, University of Gdańsk, 80-952, Gdańsk, Wita Stwosza 57, Poland.
Journal of Fluorescence
|November 15, 2013
Summary
High-accuracy simulations reveal that averaged orientation factors slightly overestimate real values in three-dimensional systems. Experimental data for Na-fluorescein and rhodamine 6G align well with theory, with deviations at higher concentrations due to dimers.
Area of Science:
- Photophysics and Fluorescence Spectroscopy
- Computational Chemistry and Simulation
- Materials Science
Background:
- Understanding energy migration in fluorescent systems is crucial for applications.
- Previous models for orientation factors and excitation probability showed discrepancies.
- Monte Carlo simulations offer a high-accuracy approach to study these phenomena.
Purpose of the Study:
- To perform high-accuracy Monte Carlo simulations of excitation probability and emission anisotropy in one-component 3D systems.
- To compare simulation results with established theoretical models (diagrammatic and Huber).
- To experimentally validate the simulation findings using Na-fluorescein and rhodamine 6G solutions.
Main Methods:
- High-accuracy Monte Carlo simulations of time-dependent excitation probability G(s)(t) and steady-state emission anisotropy rM/r0M.
- Comparison of simulation results with diagrammatic (G(s)(t)) and two-particle Huber (R(t)) models.
- Experimental measurements of emission anisotropy in glycerolic solutions of Na-fluorescein and rhodamine 6G at various excitation wavelengths.
Main Results:
- Averaged orientation factors slightly overestimate real orientation factors, differing from prior reports.
- Simulation results agree well with the Huber model R(t) but deviate from the diagrammatic model G(s)(t) at high concentrations/long times.
- Experimental data for Na-fluorescein and rhodamine 6G show excellent agreement with theory up to specific concentrations, beyond which dimer presence causes discrepancies.
- Dispersive energy migration effects were observed, with experimental anisotropies deviating from theoretical predictions under Stokes and anti-Stokes excitation.
Conclusions:
- Monte Carlo simulations provide accurate predictions for excitation probability and emission anisotropy in fluorescent systems.
- The presence of dimers significantly impacts emission anisotropy at higher concentrations.
- Wavelength-dependent deviations in experimental anisotropy suggest variations in fluorescent center 0-0 transitions.
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