Atomic Trajectories of a Bimolecular Reaction Visualized by Ultrafast Electron Diffraction

Area of Science:

• Chemical Dynamics
• Solid-State Chemistry
• Ultrafast Spectroscopy

Background:

• Observing atomic motion in bimolecular reactions at ultrafast timescales is challenging.
• High temporal and spatial resolution are crucial for detecting bond breaking and formation.

Purpose of the Study:

• To track the atomic motion during a photoinduced bimolecular disproportionation reaction.
• To visualize the real-time transformation of triiodide anions.

Main Methods:

• Utilized solid-state alignment for enhanced signal detection.
• Employed ultrafast electron diffraction (UED) for high temporal resolution.
• Applied dynamical structure refinement to reconstruct atomic trajectories.

Main Results:

• Successfully tracked the photoinduced disproportionation of triiodide anions (I3-) in real time.
• Observed bond elongation, breaking, and subsequent bond formation within a picosecond.
• Demonstrated site-dependent reaction pathways on the ultrafast timescale.

Conclusions:

• Provided an unprecedented view of atomic motion in a classic bimolecular reaction.
• Validated the use of UED and dynamical structure refinement for studying ultrafast chemical processes.
• Highlighted the importance of solid-state effects in controlling reaction dynamics.