Hokkaido University Research Profiles

Nanotechnology / Materials

Molecular-level In-situ Optical Observation of Ice Crystal Surfaces

Development of an optical microscope with atomic height resolution and in-situ observation of ice crystal surfaces

In collaboration with Olympus Engineering Corporation, we have developed an optical microscope that has atomic resolution in the height direction. We are now studying mechanisms of the growth, sublimation, and melting of ice crystals at the molecular level.

Content of research

Crystals bounded by flat surfaces grow layer by layer, irrespective of materials. Therefore, to clarify the mechanisms and kinetics of crystal growth, we need to directly observe the behavior of growing ends of molecular layers (commonly called “elementary step”). However, atomic force microscopes and electron microscopes, both of which are generally used to observe solid surfaces at the molecular level, cannot be used to observe ice crystals. To overcome this difficulty, we have developed an optical microscope that can directly visualize elementary steps with the atomic/molecular height on a flat crystal surface in a non-contact, non-destructive manner. Using this microscope, we are now working on clarifying the growth mechanisms of ice crystals and the melting of ice crystal surfaces at sub-zero temperatures (called “surface melting”) at the molecular level. In addition to ice crystals, we are also conducting a wide range of research to investigate crystal surfaces at the atomic/molecular height levels.

  • Ice crystals growing in supersaturated water vapor (like snow). Round islands on the crystal surface show elementary steps with the height of a single water molecule.

Potential for social implementation

  • ・In-situ observation of growth and melting behavior of various crystals
  • ・In-situ observation of chemical reactions on various crystal surfaces.

Appealing points to industry and local governments

・We can visualize molecular (atomic) layers on crystal surfaces. This is original technology developed by our laboratory and Olympus Engineering Corporation.
・In addition to the visualization of molecular steps, we expect that our optical microscope has a wide range of applications, including the visualization of chemical reactions on solid surfaces.