<p>Ice provides one of the most important molecular crystals in our life. Because of its critical role in science and engineering, a number of experimental studies have been conducted on ice–vacuum [1] and also on ice–vapor [2] interfaces . However, molecular-scale knowledge of the ice–water interface is still quite limited. The problem is that an ice–water interface fluctuates in space, even when the interface is held exactly at the freezing point. In addition, the interface is lost when its temperature deviates from the freezing point.</p><p></p><p>To solve this problem and to analyze the interface at the molecular level, we considered using atomic force microscopy (AFM) at the interface between ice and organic solvents. For instance, ice in contact with liquid octanol (C₈H₁₇OH) is stable at temperatures below the freezing point of ice (0°C) and above the freezing point of octanol (-16°C), although the organic solvent is not equivalent to water, we expected that it is likely to mimic some features, hopefully important features, of the ice-water interface.</p><p></p><p>We investigated different ways to keep the ice–liquid interface below 0°C on a Dimension XR Icon NanoEC microscope (Bruker) being operated at the Institute for Molecular Science. The best way we found was to cool the entire microscope placed in an acoustic enclosure. The temperature inside the box was controlled at -10 ± 5°C stable enough to take topographic images of ice films in octanol with a spatial resolution of 0.1 nm (Fig. 1). In a nitrogen vapor atmosphere, ice films exhibited a more rippled topography than those observed in octanol. The finite dissolution of water to octanol and recrystallization on ice may have helped flatten the ice–octanol interfaces. In addition to topographic imaging, force curves were measured to follow the elastic response of the ice under the AFM tip.</p><p></p><p>References</p><p>[1] J. Peng, J. Guo, R. Ma, Y. Jiang, Surf. Sci. Rept. 77, 100549 (2022).</p><p>[2] F. Tang, T. Ohto, S. Sun, J. R. Rouxel, S. Imoto, E. H. G. Backus, S. Mukamel, M. Bonn, Y. Nagata, Chem. Rev. 120, 3633 (2020).</p>