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Photoinduced gas-phase electron transfer reactions
G A Zalesskaya1, E G Sambor, N N Bely
1Institute of Molecular and Atomic Physics, National Academy of Sciences, Minsk, Belarus. smk@imaph.bas-net.by
Journal of Fluorescence
|December 24, 2004
Summary
Electron transfer quenching rates were measured for gas-phase molecules. Positive and negative temperature effects on electron transfer were observed, analyzed using Marcus-Jortner theory.
Area of Science:
- Photochemistry
- Chemical Kinetics
- Physical Chemistry
Background:
- Electron transfer is crucial in many chemical and biological processes.
- Understanding quenching mechanisms requires studying excited states.
Purpose of the Study:
- Investigate electron transfer quenching in gas-phase systems.
- Determine bimolecular rate constants and temperature dependence.
- Analyze data using Marcus-Jortner theory.
Main Methods:
- Time-resolved fluorescence spectroscopy.
- Variable-temperature measurements for eight donor-acceptor pairs.
- Gas-phase system studies (benzophenone, anthraquinone, carbazole with various quenchers).
Main Results:
- Bimolecular rate constants for electron transfer quenching were obtained.
- Quenching rates varied by three orders of magnitude with different quenchers.
- Observed both positive and negative temperature dependences for electron transfer rate constants.
Conclusions:
- Gas-phase electron transfer quenching is sensitive to quencher reactivity.
- Temperature effects on electron transfer rates can be positive or negative.
- Marcus-Jortner theory provides a framework for analyzing the observed phenomena.