Atomic site-sensitive processes in low energy ion-dimer collisions

Area of Science:

• Atomic and Molecular Physics
• Chemical Physics
• Ion-Atom Collisions

Background:

• Investigating electron capture in ion-molecule collisions is crucial for understanding chemical reactions and plasma physics.
• Argon dimer (Ar2) targets present a unique system to study projectile interactions with multiple atomic centers.

Purpose of the Study:

• To investigate electron capture processes for low energy Ar(9+) ions colliding with Ar(2) targets.
• To analyze charge sharing dynamics as a function of molecular orientation and impact parameter.
• To determine if projectiles distinguish individual atoms within the Ar2 target.

Main Methods:

• Experimental measurements of electron capture in Ar(9+) + Ar(2) collisions.
• Analysis of projectile scattering angles and molecular ion orientation.
• Comparison with Monte Carlo simulations using the classical over-the-barrier model.

Main Results:

• A preference for charge-asymmetric dissociation channels was observed.
• A strong correlation was found between projectile scattering angle and molecular ion orientation.
• Clear evidence indicates projectiles distinguish individual atoms in the target, favoring near-site capture.

Conclusions:

• The study provides evidence that Ar(9+) ions can differentiate between atoms in an Ar(2) target.
• Electron capture is favored from the atom closest to the incoming projectile.
• The findings offer new insights into the dynamics of ion-dimer collisions.