Identifying Few-Molecule Water Clusters with High Precision on Au(111) Surface

Area of Science:

• Surface science
• Physical chemistry
• Materials science

Background:

• Understanding hydrogen-bond networks in water is crucial.
• Water-solid interfaces play a vital role in many scientific fields.

Purpose of the Study:

• To directly image and determine the structure of water clusters on a Au(111) surface.
• To investigate the geometry variations of water clusters with increasing size.
• To clarify the configuration of water hexamers on metal surfaces.

Main Methods:

• Utilized low-temperature scanning tunneling microscopy (LT-STM) with a functionalized tip for molecular resolution imaging.
• Performed density functional theory (DFT) calculations with van der Waals (vdW) corrections to corroborate experimental findings.

Main Results:

• Directly imaged water clusters on Au(111) with molecular resolution.
• Identified the internal structures and size-dependent geometry variations of water clusters.
• Provided evidence for a flat configuration of water hexamers, contradicting previous theoretical predictions of a buckled structure.
• DFT calculations supported the experimental observation of flat hexamers.

Conclusions:

• The study unambiguously determined the internal structures of adsorbed water clusters on Au(111).
• Demonstrated the critical role of van der Waals interactions in the formation and stability of water-solid interfaces.
• Resolved a long-standing discrepancy regarding the structure of water hexamers on metal surfaces.