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Updated: Jul 17, 2026
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Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
Photoionization affected by chemical anisotropy
1Weizmann Institute of Science, Rehovot 76100, Israel.
The Journal of Chemical Physics
|January 11, 2007
Summary
This study reveals how rhodamine 3B fluorescence quenching by N,N-dimethyl aniline is influenced by solvent viscosity. Encounter theory accurately describes the kinetics, incorporating Marcus electron transfer rates for better predictions.
Area of Science:
- Photochemistry
- Chemical Kinetics
- Physical Chemistry
Background:
- Fluorescence quenching is a critical process in photochemistry.
- Understanding quenching kinetics in different solvents is essential for mechanistic studies.
- Previous models often used approximations that limited their applicability.
Purpose of the Study:
- To investigate the kinetic constants of rhodamine 3B quenching by N,N-dimethyl aniline.
- To fit quenching kinetics using encounter theory and Marcus transfer rates.
- To explore the influence of solvent viscosity and reactant rotation on quenching dynamics.
Main Methods:
- Extraction of kinetic constants from early quenching stages.
- Application of conventional kinetic constant definitions with radial distribution functions.
- Utilizing space-dependent encounter diffusion and Marcus transfer rates within encounter theory.
- Comparison with Collins-Kimball approximation.
Main Results:
- Kinetic constants were well-fitted by conventional definitions when considering reactant distribution and varied contact electron transfer rates.
- The rotation of reactants, faster in lower viscosity solvents, explained chemical anisotropy averaging.
- Encounter theory with Marcus rates successfully fitted the entire quenching kinetics, including long-time behavior.
- Predicted concentration dependencies for fluorescence quantum yield and Stern-Volmer constant.
Conclusions:
- Encounter theory provides a robust framework for describing fluorescence quenching kinetics.
- Solvent viscosity significantly impacts quenching dynamics through reactant rotation and anisotropy averaging.
- The study offers testable predictions for fluorescence quantum yield and Stern-Volmer constant concentration dependencies.
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