What is the surface structure of ice, and when and how it begins to melt? These problems have troubled the scientific community for a long time. A research team composed of the School of Physics of Peking University and the Light Element Quantum Materials Interdisciplinary Platform of the Beijing Huairou Comprehensive National Science Center (referred to as the Light Element Platform) used the independently developed domestic qPlus scanning probe microscope to "see" it for the first time in the world. The atomic structure of the ice surface reveals the secret of why it begins to melt at minus 153 degrees Celsius. The results were published in the international academic journal "Nature" on the evening of the 22nd.

The ice surface is an important medium for the occurrence of various natural phenomena and atmospheric reactions. It has a significant impact on the formation of ice, the decomposition of ozone in the stratosphere and the charging phenomenon of thunderclouds. However, due to the lack of atomic-scale experimental tools, the scientific community has not yet clearly answered the basic questions about the surface structure of ice. Tian Tian, a distinguished researcher at the Light Element Platform, said that the team used the qPlus scanning probe microscope to develop imaging technology that can distinguish hydrogen atoms and chemical bonds, achieving precise identification of the hydrogen bond network of water molecules on the ice surface and precise positioning of the distribution of hydrogen atoms. The detection found that the ice surface structure has both hexagonal close-packing and cubic close-packing arrangements, and the splicing and stacking form a stable network structure.

The research also revealed the mechanism of pre-melting of ice surfaces. Ice surfaces often begin to melt below zero degrees Celsius, a phenomenon known as pre-melting of ice. Professor Jiang Ying, head of the Light Element Platform, said that due to limitations of research tools, the scientific community has been unable to obtain accurate atomic-scale information. As a result, the debate surrounding the ice surface structure and pre-melting mechanism has continued for more than 170 years. International research generally believes that the temperature at which pre-melting occurs on the ice surface is above minus 70 degrees Celsius.

"Through the temperature change experiment, we 'saw' the pre-melting process of the ice surface on the atomic scale for the first time, and found that it begins to melt at minus 153 degrees Celsius." Jiang Ying said, this is very important for understanding the lubrication phenomenon of the ice surface and the formation of clouds. and the melting process of glaciers are very important.

Wang Enge, academician of the Chinese Academy of Sciences and chairman of the Light Element Platform, said that this work refreshes the long-standing traditional understanding of ice surface structure and pre-melting mechanism, and opens up a new atomic-scale perspective for ice scientific research.

"Nature" has a special report on this research. Several reviewers commented that the team's atomic-level imaging of the ice surface is an important technological innovation, and the resolution achieved is "unprecedented" in ice surface imaging. These findings may have implications for many fields such as atmospheric science and materials science. deep influence.