Inducing Transient Charge State of a Single Water Cluster on Cu(111) Surface

Abstract

The hydrated electron on solid surface is a crucial species to interfacial chemistry. We present a joint low-temperature scanning tunneling microscopy and density functional theory investigation to explore the existence of a transient hydrated electron state induced by injecting tunneling electrons into a single water nonamer cluster on Cu(111) surface. The directional diffusion of water cluster under the Coulomb repulsive potential has been observed as evidence for the emergence of the transient hydrated electron. A critical structure transformation in water cluster for the emergence of hydrated electron has been identified. A charging mechanism has been proposed based on density functional theory calculation and scanning tunneling microscope results.

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

“…The Au(111) substrate was prepared by repeated cycles of sputtering and annealing until a clean Au(111)-22 × reconstructed surface was obtained. Water molecules were deposited onto the surface of the Au(111) crystal hold at the cold STM stage around 19 K; the detailed method has been introduced previously . The tungsten tip was prepared by electrochemical etching, resulting in a typical radius of curvature about 20 nm.…”

“…Water molecules were deposited onto the surface of the Au(111) crystal hold at the cold STM stage around 19 K; the detailed method has been introduced previously. 9 The tungsten tip was prepared by electrochemical etching, resulting in a typical radius of curvature about 20 nm. The functionalization was achieved by poking the tip over small water clusters with a voltage pulse (typically −2 V with 200 ms duration) and tip extension by a few angstroms.…”

“…The water–solid interface plays an important role in a broad range of phenomena, including corrosion, catalysis, electrochemistry, and life activities. − A critical step toward fully understanding the water–solid interface is to reveal the microscopic nature of water clusters at the initial stage of water nucleation onto solid surfaces, which includes molecular conformations with atomic details, − charge hybridization, , and dynamic behaviors. − The molecular structure of a water cluster on the surface is mainly determined by the hydrogen-bond interactions between adjacent water molecules and the bonding forces between water molecules and the substrate. Individual water molecules and various clusters including dimers, , trimers, tetramers, , hexamers, and other higher order clusters, have been observed and analyzed by scanning tunneling microscope (STM) in conjunction with density functional theory (DFT). On reactive metal surfaces such as Ru and Pd, the water–substrate bonds are normally stronger than the hydrogen bond.…”

“…11−13 The molecular structure of a water cluster on the surface is mainly determined by the hydrogen-bond interactions between adjacent water molecules and the bonding forces between water molecules and the substrate. Individual water molecules 14 and various clusters including dimers, 15,16 trimers, 17 tetramers, 18,19 hexamers, 6 and other higher order clusters, 9 have been observed and analyzed by scanning tunneling microscope (STM) in conjunction with density functional theory (DFT). On reactive metal surfaces such as Ru and Pd, the water− substrate bonds are normally stronger than the hydrogen bond.…”

Rotational and Vibrational Excitations of a Single Water Molecule by Inelastic Electron Tunneling Spectroscopy

“…For example, water molecules confined in one-dimensional carbon nanotubes exhibit abnormally large permeability, and those in a biological nanopore can mediate the recognition of DNA sequences . The structure, stability, functionality, and reactivity of biomolecules and H-bonded materials ,, are closely related to the rotational and vibrational behavior of water molecules at the nanoscale.…”