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Updated: Aug 19, 2025
08:22
Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
6.9K
Few-Femtosecond C2H4+ Internal Relaxation Dynamics Accessed by Selective Excitation.
Matteo Lucchini1,2, Benoit Mignolet3, Mario Murari1,2
1Department of Physics, Politecnico di Milano, 20133 Milano, Italy.
The Journal of Physical Chemistry Letters
|November 29, 2022
Summary
Researchers used ultrafast laser pulses to study ethylene cation dissociation. They found that infrared pulses enhance fragmentation by exciting the cationic ground state, revealing ultrafast dynamics.
Area of Science:
- Physical Chemistry
- Chemical Physics
- Molecular Dynamics
Background:
- Ethylene cation dissociation is a key model for understanding complex chemical reactions.
- The precise mechanisms of energy redistribution and rate-determining steps in this process remain largely unknown.
Purpose of the Study:
- To elucidate the ultrafast dynamics of ethylene cation dissociation.
- To identify the role of internal energy conversion and conical intersections in the initial stages of relaxation.
Main Methods:
- Utilizing few-femtosecond extreme-ultraviolet (XUV) pulses to excite specific superpositions of ethylene cation states.
- Employing time-delayed infrared (IR) pulses to probe excited-state dynamics and fragmentation pathways.
Main Results:
- Demonstrated that IR pulse photoexcitation of the ground state (GS) leads to a 'hot' GS upon relaxation, increasing fragmentation.
- Observed that IR probing reveals geometry-dependent photoexcitation, providing insights into ultrafast dynamics.
Conclusions:
- The study provides critical insights into the initial 20 fs of nonradiative relaxation in ethylene cation.
- Identified the involvement of specific conical intersections (planar or twisted) in the dissociation pathway.
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