Spectroscopic observation and structure of CS2 dimer.

Area of Science:

• Molecular Spectroscopy
• Chemical Physics
• Intermolecular Forces

Background:

• Previous studies on small molecule dimers like (CO(2))(2), (N(2)O)(2), and (OCS)(2) suggested planar, slipped-parallel structures.
• Understanding the structural and dynamical properties of weakly bound van der Waals complexes is crucial in molecular physics.

Purpose of the Study:

• To investigate the structure and intermolecular dynamics of the carbon disulfide (CS(2)) dimer using high-resolution infrared spectroscopy.
• To determine the equilibrium geometry and vibrational frequencies of the CS(2) dimer.

Main Methods:

• Utilizing a tunable diode laser spectrometer to record infrared spectra of the CS(2) dimer.
• Forming the weakly bound CS(2) complex in a pulsed supersonic slit-jet expansion of carbon disulfide in helium.
• Analyzing the rotational structure of observed vibrational bands to deduce molecular symmetry and geometry.

Main Results:

• Observed infrared spectra in the region of the CS(2) ν(3) fundamental band (∼1535 cm(-1)).
• Determined a cross-shaped structure with D(2d) symmetry for the CS(2) dimer, contrasting with previously observed planar geometries.
• Identified two vibrational bands: the fundamental (C-S asymmetric stretch) and a combination band.
• Calculated an intermolecular center of mass separation (C-C distance) of 3.539(7) Å.
• Assigned an intermolecular torsional bending mode frequency of 10.96 cm(-1).

Conclusions:

• The CS(2) dimer adopts a non-planar, cross-shaped structure, challenging previous assumptions based on similar dimers.
• This study provides the first high-resolution spectroscopic characterization of the CS(2) dimer, detailing its structural and vibrational properties.
• The findings contribute to a deeper understanding of non-covalent interactions and the structural diversity of van der Waals molecules.