Metastable BrO2+ and NBr2+ molecules in the gas phase

Area of Science:

• Physical Chemistry
• Atomic and Molecular Physics
• Materials Science

Background:

• Doubly charged gas-phase molecules are rare and challenging to synthesize and characterize.
• Understanding the stability and properties of such species is crucial for advancing molecular physics and chemistry.

Purpose of the Study:

• To experimentally produce and characterize novel doubly charged molecules BrO(2+) and NBr(2+).
• To theoretically investigate the electronic structure, stability, and fragmentation pathways of these molecules.
• To determine the adiabatic double ionization energies for BrO and NBr.

Main Methods:

• Ion beam sputtering of RbBr and NH(4)Br targets using energetic oxygen ions.
• Analysis of positive ion mass spectra using a magnetic-sector secondary ion mass spectrometer.
• High-level ab initio calculations for ground and excited electronic states.

Main Results:

• Successful synthesis and detection of BrO(2+) and NBr(2+) at half-integer m/z values.
• Ground states of NBr(2+) and BrO(2+) confirmed as long-lived metastable molecules with significant well depths.
• Calculated lifetimes indicate stability against tunneling for specific vibrational levels.
• Predicted equilibrium bond lengths and vibrational frequencies for both molecular ions.
• Calculated adiabatic double ionization energies of 30.73 eV for BrO and 29.08 eV for NBr.

Conclusions:

• The study presents the first experimental evidence and theoretical validation of doubly charged BrO(2+) and NBr(2+) molecules.
• These novel species exhibit significant metastability, suggesting potential for further investigation in molecular ion chemistry.
• The findings contribute to the understanding of molecular stability and fragmentation dynamics in highly charged systems.