▎ 摘　　要

Properties of thin water films on Pt(111) with and without monolayer graphene (MLG) in between were investigated using reflection high-energy electron diffraction, time-of-flight secondary-ion mass spectrometry, and temperature-programmed desorption. During water deposition at 100 K, water molecules in direct contact with the MLG/Pt(111) surface tend to be arranged locally by directing free OH groups toward the substrate. However, such species is formed initially only in the submonolayer regime on bare Pt(111). This behavior is likely to be associated with hydrophobic hydration. Crystallites of cubic and hexagonal ices with (111) and (0001) orientations, respectively, are grown epitaxially on the Pt(111) and MLG/Pt(111) substrates with considerable stacking disorders. The H-down water species remain on Pt(111) after crystallization, although they disappear completely from the MLG/Pt(111) substrate. These behaviors indicate that the water monolayer is equilibrated with a premelting layer on the ice crystallite. It behaves like a liquid and plays a role in the ripening of pre-existing crystallites during water vapor deposition. Consequently, the potential field and wettability of the Pt(111) substrate are not transmitted through the MLG layer formed on it, as far as the liquidlike water formed at cryogenic temperature is concerned.