Cold Molecular Ions via Autoionization below the Dissociation Limit

Area of Science:

• Physical Chemistry
• Molecular Physics
• Quantum Chemistry

Background:

• Certain molecules exhibit bond dissociation energies exceeding their ionization energies.
• This unique property allows for population of bound electronic states above the ionization threshold.

Purpose of the Study:

• To investigate the efficient production of translationally and internally cold molecular ions.
• To demonstrate a novel method for generating cold ions using resonant excitation.
• To determine the bond dissociation energy relative to the ionization energy for dysprosium monoxide (DyO).

Main Methods:

• Utilizing strong, resonant transitions to populate bound molecular levels above the ionization energy.
• Leveraging autoionization as the primary decay channel for excited states.
• Experimentally measuring the energy difference between the bond dissociation and ionization energies for DyO.

Main Results:

• Achieved very high efficiency in producing translationally cold molecular ions from cold neutral molecules.
• Demonstrated the exclusive population of the lowest rotational level in internally cold molecular ions.
• Determined the lowest bond dissociation energy of DyO to be 0.0831(6) eV above its ionization energy.

Conclusions:

• This resonant excitation and autoionization pathway offers a highly efficient route to cold molecular ions.
• The method allows for precise control over the internal energy states of the resulting ions.
• Dysprosium monoxide serves as a key example showcasing the potential of this technique.