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Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
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Multi-faceted spectroscopic mapping of ultrafast nonadiabatic dynamics near conical intersections: A computational
Kewei Sun1, Weiwei Xie2, Lipeng Chen3
1School of Science, Hangzhou Dianzi University, Hangzhou 310018, China.
The Journal of Chemical Physics
|November 10, 2020
Summary
This study reveals spectroscopic fingerprints of nonadiabatic dynamics in pyrazine's excited states. Combining multiple spectroscopic techniques offers a comprehensive view of these ultrafast processes.
Area of Science:
- Physical Chemistry
- Quantum Dynamics
- Spectroscopy
Background:
- Nonadiabatic dynamics and conical intersections are crucial in understanding excited-state processes in molecules like pyrazine.
- Characterizing the behavior of optically dark states is essential for a complete picture of molecular photophysics.
Purpose of the Study:
- To investigate the spectroscopic signatures of nonadiabatic dynamics at conical intersections in pyrazine's excited singlet states.
- To establish how different spectroscopic techniques can reveal key features of photoinduced dynamics.
Main Methods:
- Utilized two ab initio models of conical intersections in pyrazine (two-state/five-mode and three-state/nine-mode).
- Simulated signals from time- and frequency-resolved fluorescence, transient absorption pump-probe, and electronic two-dimensional spectroscopy.
- Calculated signals using third-order response functions evaluated with the multiple Davydov ansatz.
Main Results:
- Established spectroscopic signatures for the optically dark Au state in pyrazine.
- Demonstrated that electronic/nuclear populations, coherences, and energy transfer processes are imprinted in spectroscopic signals.
- Showed that combining multiple spectroscopic techniques provides a comprehensive understanding of nonadiabatic dynamics.
Conclusions:
- A combination of spectroscopic methods is effective for elucidating nonadiabatic dynamics at conical intersections.
- Time- and frequency-resolved fluorescence spectroscopy offers excellent visualization of nonadiabatic dynamics, given sufficient time resolution.
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