Structural and Electronic Properties of Anionic (ThO₂)_n^- (n = 2-4) Clusters

Area of Science:

• Materials Science
• Computational Chemistry
• Nuclear Engineering

Background:

• Thorium dioxide nanomaterials are of interest for catalysis and nuclear fuel.
• Understanding their electronic structure is crucial for property investigation.
• Small cluster units provide fundamental insights into bulk properties.

Purpose of the Study:

• Investigate the geometric and electronic structure of neutral and anionic thorium dioxide clusters (ThO2)n, n = 2, 3, 4.
• Compare structural isomers and electronic properties between neutral and anionic clusters.
• Correlate computational findings with experimental anion photoelectron spectroscopy data.

Main Methods:

• Joint computational and experimental study.
• Density Functional Theory (DFT) calculations for geometric and electronic structure.
• Anion photoelectron spectroscopy (aPES) for experimental validation.
• Analysis of highest occupied molecular orbital (HOMO) and vertical detachment energy (VDE).

Main Results:

• Identified distinct global minimum structures and isomer distributions for neutral vs. anionic clusters.
• HOMO nature influences structural differences between neutral and anionic species.
• Computed VDE values closely matched experimental aPES spectral peaks.
• Spectral features beyond VDE were attributed to contributions from multiple structural isomers.

Conclusions:

• The electronic structure, particularly the HOMO, dictates the structural preferences of thorium dioxide clusters.
• Computational VDE calculations accurately predict experimental aPES spectra.
• Structural isomers play a role in the detailed spectral features of anionic clusters.
• This work provides a foundation for designing thorium dioxide-based nanomaterials.