2014 Volume 31 Issue 3 Pages 100-
We and Olympus Engineering Co.，Ltd. developed laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM), by which elementary steps (0.37 nm in thickness) on ice crystal surfaces can be visualized in situ at air-ice interfaces. Using LCM-DIM, we observed surface melting processes of ice crystals in situ, and found that an ice basal face grown from water vapor exhibits two types of quasi-liquid layer (QLL) phases that have different morphologies and dynamics. In this review, we show how these QLL phases emerge from an ice basal face. We found that round liquid-like drops (an α-QLL phase) emerge from outcrops of screw dislocations, and that thin liquid-like layers (a β-QLL phase) appear from crystal surfaces where many microdefects are embedded. These results strongly suggest that strain caused by lattice defects induces the appearance of both QLL phases. In addition, we also found that a β-QLL phase spontaneously forms at the interface between an α-QLL phase and a basal face when the diameter of an α-QLL phase becomes larger than several 10 µm. This result implies that a β-QLL phase has an intermediate structure between those of an α-QLL phase and a basal face.
