Intrinsic reconstruction of ice-I surfaces

Area of Science:

• Surface science
• Materials science
• Physical chemistry

Background:

• Precise atomic structure of ice surfaces is crucial for understanding phenomena like ice growth, melting, and chemical reactions.
• No definitive ice surface structure has been established, hindering mechanistic understanding.
• Ice Ih(0001) and Ic(111) surfaces are key models for studying ice properties.

Purpose of the Study:

• To characterize the atomic structures of ice Ih(0001) and Ic(111) surfaces.
• To elucidate the ordering of hydrogen atoms on ice surfaces.
• To explain the mechanisms behind ice surface reconstruction.

Main Methods:

• Noncontact atomic force microscopy (NC-AFM) was employed for high-resolution surface imaging.
• Experimental conditions were varied to assess the influence of ice thickness and substrate.
• Atomic-level surface topography was analyzed to determine structural arrangements.

Main Results:

• A short-range (2 × 2) ordered arrangement of topmost hydrogen atoms was observed on both ice Ih(0001) and Ic(111) surfaces.
• This hydrogen ordering was found to be independent of ice thickness and the growth substrate.
• Surface reconstruction was attributed to electrostatic repulsion between non-hydrogen-bonded water molecules, leading to a reduced number of topmost hydrogen atoms and distorted honeycomb structures.

Conclusions:

• The study establishes a short-range (2 × 2) ordered structure for the topmost hydrogen atoms on common ice surfaces.
• Electrostatic repulsion is identified as the driving force for surface reconstruction, involving a reduction in hydrogen atoms and lattice distortion.
• This finding provides critical insights into the fundamental atomic arrangements governing ice surface behavior and reactivity.