Long-range dispersion C₆ coefficient for SF₆ dimer: Experimental and theoretical study.

Area of Science:

• Chemical Physics
• Atomic and Molecular Physics

Background:

• Accurate determination of intermolecular forces is crucial for understanding material properties.
• Long-range dispersion coefficients, like the C6 coefficient, govern van der Waals interactions between molecules.
• Sulfur hexafluoride (SF6) is a molecule with significant industrial applications, making its dimer interactions of interest.

Purpose of the Study:

• To experimentally measure the long-range dispersion C6 coefficient for the SF6 dimer.
• To theoretically calculate the C6 coefficient using advanced computational methods.
• To compare experimental and theoretical results for validation and to refine understanding of SF6 dimer interactions.

Main Methods:

• Experimental measurement utilizing supersonic pulse jet expansion into a vacuum.
• Analysis of time-of-flight spectra correlated with a dynamic jet model and intermolecular potential parameters.
• Theoretical calculation employing the linearly approximated explicitly correlated coupled-cluster singles and doubles (CCSD(F12)) method.
• Application of the Casimir-Polder formula for theoretical C6 coefficient determination.

Main Results:

• The C6 dispersion coefficient for the SF6 dimer was successfully extracted from experimental data.
• Theoretical calculations provided a C6 coefficient value for the SF6 dimer.
• Excellent agreement was observed between the experimentally determined and theoretically calculated C6 coefficients.

Conclusions:

• The experimental measurement and theoretical calculation of the C6 dispersion coefficient for the SF6 dimer show good agreement.
• The study validates the reliability of the supersonic jet expansion technique for measuring intermolecular potential parameters.
• The findings contribute to a more accurate understanding of van der Waals forces in SF6 dimers.