Electron Localization in Dissociating H_{2}^{+} by Retroaction of a Photoelectron onto Its Source

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Photochemistry

Background:

• Investigating the dissociation dynamics of simple molecular ions is crucial for understanding fundamental chemical and physical processes.
• Single ionization of hydrogen molecular ions (H_{2}^{+}) provides a benchmark system for studying electron-molecular interactions.

Purpose of the Study:

• To experimentally investigate the dissociation asymmetry of H_{2}^{+} following near-threshold single photon ionization.
• To compare experimental findings with theoretical predictions regarding symmetry breaking in molecular dissociation.

Main Methods:

• Experimental setup involving near-threshold single photon ionization of H_{2}^{+}.
• Analysis of fragment ion (p^{+} and H^{0}) and photoelectron momenta to determine dissociation dynamics.
• Comparison with theoretical models, including classical photoelectron treatment.

Main Results:

• Observed asymmetric ejection of the proton (p^{+}) and neutral hydrogen atom (H^{0}) during H_{2}^{+} dissociation.
• A distinct preference for p^{+} ejection in the direction of the escaping photoelectron.
• Symmetry breaking is most pronounced at very low photoelectron energies.

Conclusions:

• The experimental results confirm theoretical predictions of symmetry breaking in H_{2}^{+} dissociation.
• The long-range Coulomb potential's retroaction on the dissociating ion is identified as the mechanism inducing asymmetry.
• This study provides insights into electron-molecular interactions and dissociation dynamics.