Observation of the "missing" polar OCS dimer

Area of Science:

• Chemical Physics
• Molecular Spectroscopy
• Quantum Chemistry

Background:

• The carbonyl sulfide (OCS) dimer exists in various isomeric forms, with experimental and theoretical studies yielding conflicting results regarding their structures and stability.
• Previous research has not definitively identified or characterized the polar isomer of the OCS dimer, leading to ambiguities in understanding its properties.

Purpose of the Study:

• To identify and characterize the polar isomer of the OCS dimer using infrared spectroscopy.
• To provide experimental data that can resolve discrepancies in previous studies of OCS dimer isomers.
• To facilitate future investigations into the energetics and interconversion barriers of OCS dimer isomers.

Main Methods:

• High-resolution infrared spectroscopy was employed to detect new spectral features.
• The observed infrared band at 2069.3 cm-1 was analyzed and assigned to a specific OCS dimer isomer.

Main Results:

• A novel infrared absorption band at 2069.3 cm-1 was successfully observed.
• This band was conclusively assigned to the long-sought polar isomer of the OCS dimer.
• The experimental data provide a basis for understanding previously observed discrepancies in OCS dimer studies.

Conclusions:

• The identification of the polar OCS dimer isomer provides crucial experimental evidence.
• This discovery will enable direct observation of the polar (OCS)2 microwave spectrum.
• The findings are expected to stimulate new theoretical investigations into OCS dimer energetics and isomerization pathways.