Postcollision multifragmentation in fullerene-surface impact: Microscopic insights via molecular dynamics simulations

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Physics

Background:

• Postcollision multifragmentation is a phenomenon where excited molecules break apart after interacting with a surface.
• Previous experimental studies observed this process in C60 collisions with surfaces.

Purpose of the Study:

• To computationally investigate and reproduce the experimentally observed postcollision multifragmentation of C60 molecules.
• To elucidate the mechanisms and timing of fragment formation in C60-surface collisions.

Main Methods:

• Molecular dynamics simulations were performed for near-grazing collisions of C60 with a gold surface at 300 eV impact energy.
• Analysis included mass-resolved kinetic energy distributions and time-dependent yield curves of fragment ions.

Main Results:

• Simulations successfully reproduced key experimental characteristics of postcollision multifragmentation.
• A precursor-mediated, velocity-correlated, delayed fragmentation event was identified along the outgoing trajectory.
• Formation of larger fragments (n ≥ 5) occurred 2-20 ps after surface departure, at distances of 3-30 nm.

Conclusions:

• The study confirms that molecular dynamics simulations can accurately model postcollision multifragmentation.
• The delayed fragmentation is attributed to structural transformations of the excited C60 precursor.
• Multifragmentation events were largely simultaneous and occurred postcollision, away from the surface.