Extended Data Fig. 3: The long-range order of superstructures.
From: Imaging surface structure and premelting of ice Ih with atomic resolution
a, The constant-frequency-shift AFM image of the overall ice surface, acquired at the set point of −100 mHz. Two zoom-in areas within different terraces are spaced 170 nm apart, indicated by letters b and c. b, c, Constant-height AFM images corresponding to the insets in a, depicting perfect superstructures with the same orientation. Superstructures exhibit long-range order and could extend across entire terraces. The orange and yellow triangles represent tetrahedron structures in different stacking types.