Structural assignment of small cationic silver clusters by far-infrared spectroscopy and DFT calculations

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• Understanding the structure of small metal clusters is crucial for catalysis and materials science.
• Cationic silver clusters (Ag_n⁺) exhibit unique electronic and geometric properties.
• Previous studies have provided partial structural information for smaller silver clusters.

Purpose of the Study:

• To determine the precise structures of cationic silver clusters Ag_n⁺ for n = 3-13.
• To refine the understanding of structural isomerism in small metal clusters.
• To investigate the growth patterns of cationic silver clusters and compare them with other coinage metal clusters.

Main Methods:

• Global structure search using the CALYPSO method.
• Local optimization of isomers with the meta GGA functional TPSS.
• Comparison of experimental far-infrared multiple photon dissociation spectra with calculated harmonic vibrational spectra.

Main Results:

• The structures of cationic silver clusters (Ag_n⁺, n = 3-13) were elucidated.
• The results are largely consistent with prior ion mobility and photodissociation studies for n = 3-11.
• Several previously considered structural isomers were excluded, highlighting the power of combined experimental and computational approaches.

Conclusions:

• The combination of far-infrared spectroscopy and computational methods provides a robust approach for definitive structural identification of metal clusters.
• The study refines the understanding of silver cluster structural evolution and growth.
• Differences in growth patterns between cationic silver and other coinage metal clusters were identified.