Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 49: Oxide and Insulator Interfaces I

O 49.10: Vortrag

Mittwoch, 20. März 2024, 12:45–13:00, MA 144

Imaging surface structure and premelting of hexagonal ice with atomic resolution — •Jiani Hong, Ye Tian, Tiancheng Liang, Xinmeng Liu, Limei Xu, Enge Wang, and Ying Jiang — School of Physics, Peking University, Beijing, P. R. China

The ice surfaces are closely relevant to many physical and chemical properties of ice, such as melting, freezing, friction, gas uptake, and atmospheric reaction. Despite massive experimental and theoretical investigations, the exact atomic structure of the ice interface still remains elusive due to the vulnerable surface hydrogen-bonding network and the complicated premelting process. Here, we realize the first atomic-resolution imaging of basal surface structure of hexagonal water ice by using qPlus-based cryogenic atomic force microscopy with a CO-functionalized tip. We find that the crystalline ice-Ih surface is composed of mixed Ih- and Ic-stacking nanodomains, forming periodic superstructures. DFT reveals that such a reconstructed ice surface is stabilized over the ideal ice surface mainly by minimizing the electrostatic repulsion between dangling OH bonds at the surface. Moreover, we find that the ice surface gradually becomes disordered with increasing temperature in experiment, revealing the onset of the premelting process. The surface premelting occurs from the defective boundaries between the Ih and Ic domains and can be promoted by the formation of a planar local structure. Those results put an end to the longstanding debate on the ice surface structure and shed new light on the molecular origin of ice premelting, which may lead to a paradigm shift in the understanding of ice physics and chemistry.

Keywords: qPlus-based cryogenic atomic force microscopy; hexagonal water ice (Ih); first atomic structure of ice-Ih surface; proton ordering; ice premelting