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Ultrafast isomerization initiated by X-ray core ionization
Chelsea E Liekhus-Schmaltz1,2, Ian Tenney1,2, Timur Osipov3
1Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA.
Nature Communications
|September 11, 2015
Summary
Proton motion in hydrocarbons is crucial for mitigating X-ray damage. This study reveals rapid proton redistribution in acetylene within 12 femtoseconds after X-ray ionization, impacting molecular dynamics.
Area of Science:
- Physical Chemistry
- Molecular Dynamics
- Photochemistry
Background:
- Proton migration is vital in hydrocarbon photochemistry.
- Rapid proton motion can reduce radiation damage from X-ray absorption.
- This phenomenon is key for high-fidelity biomolecular structure determination using X-ray-free electron lasers.
Purpose of the Study:
- To investigate X-ray-initiated isomerization of acetylene as a model for hydrocarbon proton dynamics.
- To capture transient proton motion following X-ray ionization.
Main Methods:
- Time-resolved measurements using X-ray ionization of carbon K-shell electrons.
- Coulomb explosion imaging with a delayed X-ray pulse to record fragment momenta.
- Construction of a 'molecular movie' from time-delayed snapshots.
Main Results:
- Observed substantial proton redistribution in acetylene within the first 12 femtoseconds.
- Captured the dynamics of proton motion after X-ray ionization.
Conclusions:
- Significant proton motion occurs on a timescale comparable to Auger relaxation.
- Findings provide insights into ultrafast proton dynamics in hydrocarbons relevant to radiation damage mitigation.
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