Hydrogen scrambling and high propensity for multiple neutral emissions from 1,3-butadiene dication

Area of Science:

• Physical Chemistry
• Chemical Physics
• Molecular Dynamics

Background:

• Understanding the dissociation dynamics of small conjugated molecules is crucial for chemical physics.
• Dications formed via double ionization exhibit complex fragmentation patterns.
• 1,3-butadiene (C4H6) is the simplest conjugated diene, serving as a fundamental model system.

Purpose of the Study:

• To investigate the two-body dissociation of 1,3-butadiene dications formed by ion-impact ionization.
• To elucidate the role of neutral particle emission (H, H2, C2H2) in the fragmentation process.
• To explore the influence of hydrogen scrambling and migration on dication stability and dissociation.

Main Methods:

• Experimental study using coincidence time-of-flight (TOF) technique.
• Ion-impact ionization with energetic Xe3+ projectiles.
• Theoretical support through ab initio molecular dynamics simulations.

Main Results:

• 1,3-butadiene dications show a high propensity for neutral particle emission before two-body dissociation.
• Asymmetric two-body breakup is twice as probable after neutral fragment emission compared to intact dications.
• Experimental evidence suggests the formation of multiple precursor dication structures due to hydrogen scrambling.

Conclusions:

• Neutral particle emission is a dominant dissociation pathway for 1,3-butadiene dications.
• Hydrogen scrambling plays a significant role in the fragmentation dynamics and structural diversity of dications.
• Molecular dynamics simulations support experimental findings on the interplay of neutral emission, scrambling, and migration.