Exploring three-body fragmentation of acetylene trication

Area of Science:

• Atomic and Molecular Physics
• Chemical Physics
• Quantum Mechanics

Background:

• Understanding molecular ion fragmentation is crucial for plasma physics and astrophysics.
• Previous studies have explored dissociation dynamics of small molecular ions.
• The specific breakup mechanisms of triply charged acetylene ions ([C2H2]3+) require further investigation.

Purpose of the Study:

• To experimentally investigate the three-body breakup of [C2H2]3+ ions.
• To differentiate between concerted and sequential dissociation pathways.
• To determine the kinetic energy release for specific fragmentation channels and unimolecular decay.

Main Methods:

• Recoil ion momentum spectroscopy was employed to study the breakup dynamics.
• Collisions between [C2H2]3+ and Xe9+ at 0.5 atomic units of velocity were analyzed.
• Ab initio calculations were performed to generate potential energy surfaces for molecular intermediates.

Main Results:

• Observed three-body breakup channels: (H+, C+, CH+) and (H+, H+, C2+).
• The (H+, C+, CH+) channel exhibited both concerted and sequential breakup modes.
• The (H+, H+, C2+) channel proceeded exclusively via a concerted mode.
• Kinetic energy release for the sequential breakup of the [C2H]2+ intermediate was determined.
• Ab initio calculations revealed a metastable state in [C2H]2+ with two dissociation pathways.

Conclusions:

• Experimental results for the [C2H2]3+ breakup are in good agreement with ab initio calculations.
• The study successfully elucidated the distinct mechanisms governing different fragmentation channels.
• This work provides valuable insights into the dissociation dynamics of highly charged small molecules.