Structure and stability of the negative hydrogen molecular ion

Area of Science:

• Chemical Physics
• Molecular Spectroscopy
• Quantum Chemistry

Background:

• The hydrogen molecule anion (H2-) is a fundamental system in quantum chemistry.
• Understanding its stability and decay mechanisms is crucial for molecular physics.
• Metastability in molecular anions is often linked to rotational excitation.

Purpose of the Study:

• To image the rovibrational wave function of the metastable H2- ion.
• To experimentally determine the internuclear separation and decay pathway of H2-.
• To quantify the angular momentum contributing to the metastability of H2-.

Main Methods:

• Coulomb explosion imaging technique.
• Analysis of dissociation products from H2-.
• Determination of internuclear distance and angular momentum from experimental data.

Main Results:

• Confirmed a large internuclear separation of approximately 6 a.u. for H2-.
• Observed decay via autodetachment, not spontaneous dissociation.
• Measured a high angular momentum (J = 25 ± 2) in the H2 products.

Conclusions:

• The metastability of H2- is directly linked to its significant rotational excitation.
• Coulomb explosion provides a powerful tool for probing molecular wave functions.
• Experimental results align with theoretical predictions for H2- properties.