Vibronic coupling in energy transfer dynamics and two-dimensional electronic-vibrational spectra.
Eric A Arsenault1, Addison J Schile1, David T Limmer1
1Department of Chemistry, University of California, Berkeley, California 94720, USA.
The Journal of Chemical Physics
|August 8, 2021
Summary
We developed a heterodimer model to study vibronic coupling mechanisms impacting energy transfer. Two-dimensional electronic-vibrational (2DEV) spectroscopy reveals distinct signatures for Franck-Condon and Herzberg-Teller activity, aiding experimental determination of energy transfer pathways.
Area of Science:
- Quantum chemistry
- Spectroscopy
- Theoretical chemistry
Background:
- Vibronic coupling significantly influences energy transfer in molecular systems.
- Understanding specific vibronic coupling mechanisms is crucial for controlling energy transfer processes.
- Distinguishing between different vibronic coupling types, such as Franck-Condon and Herzberg-Teller, is experimentally challenging.
Purpose of the Study:
- To introduce a theoretical model for studying multiple vibronic coupling mechanisms in a heterodimer.
- To investigate the impact of Franck-Condon and Herzberg-Teller vibronic coupling on energy transfer.
- To utilize two-dimensional electronic-vibrational (2DEV) spectroscopy to identify and differentiate these coupling mechanisms.
Main Methods:
- Development of a heterodimer model incorporating local electron-phonon coupling (Franck-Condon) and vibrational mode-dependent transition dipole moments (Herzberg-Teller).
- Computation of two-dimensional electronic-vibrational (2DEV) spectra for the model system.
- Analysis of spectral features, including excitonic structure and side-band transitions.
- Comparison of quantum beating patterns derived from simulated 2DEV spectra.
Main Results:
- 2DEV spectra exhibit distinct static and dynamic signatures for both Franck-Condon and Herzberg-Teller vibronic coupling.
- Franck-Condon activity influences the observed excitonic structure.
- Herzberg-Teller activity leads to significant side-band transitions mirroring lower-energy excitonic structures.
- Quantum beating patterns analyzed from 2DEV spectra provide insights into the energy transfer mechanism.
Conclusions:
- 2DEV spectroscopy is a powerful tool for elucidating the mechanisms of vibronic coupling in energy transfer.
- The developed heterodimer model allows for explicit study of different vibronic coupling contributions.
- This work provides a framework for experimentally determining the specific roles of Franck-Condon and Herzberg-Teller coupling in energy transfer processes.
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