Differential electron emission from polycyclic aromatic hydrocarbon molecules under fast ion impact

Area of Science:

• Atomic and Molecular Physics
• Plasma Physics
• Physical Chemistry

Background:

• The interaction of energetic ions with polycyclic aromatic hydrocarbons (PAHs) is crucial for understanding astrophysical environments and materials science.
• Previous studies have explored electron emission from simpler targets, but detailed investigations on complex PAHs are less common.

Purpose of the Study:

• To measure and analyze the double differential electron emission cross sections for coronene and fluorene upon fast bare oxygen ion impact.
• To compare the electron emission characteristics of these PAHs with simpler targets and investigate the role of collective excitations like plasmon resonance.

Main Methods:

• Experimental measurement of energy and angular distributions of absolute double differential electron emission cross sections.
• Theoretical calculations using the first-order Born approximation with correct boundary conditions (CB1).
• Analysis of forward-backward angular asymmetry to identify plasmon resonance signatures.

Main Results:

• Coronene exhibited distinct low-energy electron angular distributions compared to simpler targets, suggesting collective excitation effects.
• Fluorene's electron emission patterns were more similar to simpler targets, with no clear plasmon resonance signature observed.
• Theoretical calculations generally agreed with experimental data, except for low-energy electrons from coronene, highlighting the importance of collective effects.

Conclusions:

• The study reveals differences in electron emission dynamics between coronene and fluorene, with coronene showing evidence of plasmon resonance.
• Collective excitation plays a significant role in the interaction of energetic ions with complex PAH molecules.
• The findings contribute to a deeper understanding of ion-molecule interactions and the physical properties of PAHs.