On the possibility of enhanced multiple ionization near conical intersections

Area of Science:

• Physical Chemistry
• Chemical Physics
• Molecular Dynamics

Background:

• Transient laser-induced fragmentation studies investigate molecular behavior under specific energy conditions.
• Photoexcited 1,3-cyclohexadiene exhibits isomerization, a process involving structural rearrangement.
• Conical intersections (CoIns) are critical points in molecular potential energy surfaces where electronic states become degenerate, leading to non-adiabatic transitions.

Purpose of the Study:

• To explain the observation of unexpectedly high fragment velocities during the isomerization of photoexcited 1,3-cyclohexadiene.
• To investigate the role of electronic and ionic structure near conical intersections in influencing molecular fragmentation dynamics.
• To propose experimental methods for further elucidation and control of this behavior.

Main Methods:

• Theoretical exploration of molecular electronic and ionic structures in the vicinity of conical intersections.
• Analysis of transient laser-induced fragmentation data.
• Proposal of experimental tests to probe fragmentation mechanisms.

Main Results:

• Observed high velocities in fragments of photoexcited 1,3-cyclohexadiene at pump-probe delays corresponding to passage through a conical intersection.
• Identified potential explanations linked to the molecular structure and electronic states near CoIns.

Conclusions:

• The electronic and ionic structure near conical intersections significantly influences the dynamics of laser-induced fragmentation and isomerization.
• Further experimental investigations are needed to fully understand and potentially control these high-velocity fragmentation events.
• Understanding these dynamics is crucial for controlling chemical reactions at the molecular level.