Infrared bands of CS₂ dimer and trimer at 4.5 μm.

Area of Science:

• Spectroscopy
• Chemical Physics
• Molecular Spectroscopy

Background:

• Carbon disulfide (CS2) is a molecule with significant interest in chemical physics.
• Understanding the structure and vibrational properties of CS2 clusters is crucial for molecular science.
• Previous studies identified stable isomers for CS2 dimer and trimer.

Purpose of the Study:

• To observe and analyze new infrared bands of (CS2)2 and (CS2)3 complexes.
• To investigate the vibrational shifts and assignments of these complexes.
• To utilize quantum cascade laser spectroscopy for high-resolution analysis.

Main Methods:

• Formation of (CS2)2 and (CS2)3 complexes in a pulsed supersonic slit-jet expansion.
• Utilizing a quantum cascade laser for infrared spectroscopy in the 4.5 µm region.
• Analyzing observed vibrational bands and their shifts.

Main Results:

• Observed new infrared bands for (CS2)2 and (CS2)3 near the CS2 monomer's ν1 + ν3 combination band.
• The (CS2)2 dimer exhibited a small vibrational shift (-0.844 cm-1) for its doubly degenerate band.
• The (CS2)3 trimer showed larger shifts, with two parallel bands (-8.845 cm-1, +16.681 cm-1) and one perpendicular band (-8.953 cm-1).

Conclusions:

• The study successfully observed and characterized new infrared spectral features of carbon disulfide dimers and trimers.
• The observed vibrational shifts provide valuable data for understanding the intermolecular interactions and structures of these clusters.
• Group theoretical arguments were applied to discuss vibrational assignments, particularly for the trimer's parallel bands.