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Excited State Relaxation Dynamics in Benzophenone and meta-Methyl Benzophenone Revealed by Time-Resolved
Wenping Wu1,2, Yukun Dan1,2, Yuhuan Tian1,2
1State Key Laboratory of Chemical Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, Liaoning 116023, China.
The Journal of Physical Chemistry. A
|April 6, 2026
Summary
Ultrafast electronic relaxation in benzophenone derivatives was studied. Photoexcitation leads to rapid internal conversion and intersystem crossing, with methyl substitution influencing decay dynamics.
Area of Science:
- Photochemistry
- Molecular Dynamics
- Spectroscopy
Background:
- Benzophenone and its derivatives are key molecules for studying excited-state dynamics.
- Understanding ultrafast electronic relaxation is crucial for controlling photochemical reactions.
Purpose of the Study:
- To investigate the ultrafast electronic relaxation dynamics of benzophenone and meta-methyl benzophenone after photoexcitation.
- To elucidate the role of methyl substitution and excitation energy on these dynamics.
Main Methods:
- Femtosecond time-resolved photoelectron spectroscopy.
- Ultraviolet photoexcitation at specific wavelengths (267.6 and 241.0 nm).
Main Results:
- Direct excitation of the S2(1ππ*) state decays rapidly (50 ± 10 fs) to the S1(1nπ*) state via internal conversion.
- The S1(1nπ*) state decays through intersystem crossing to triplet states (T2 and T1) and internal decay, with distinct time constants for benzophenone and meta-methyl benzophenone.
- Methyl substitution and excitation energy affect the excited-state decay pathways.
Conclusions:
- The study provides detailed insights into the complex decay mechanisms of photoexcited benzophenone derivatives.
- Ultrafast internal conversion and intersystem crossing are dominant relaxation pathways.
- Methyl substitution significantly impacts the temporal evolution of excited states.
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