Ice is likely the most ubiquitous solid in the Universe, yet even here on Earth its surfaces contains many mysteries. At atmospheric pressure, the stable form of ice is hexagonal ice <i>I<sub>h</sub></i>. Hexagonal ice has three dominant face: the basal face familiar as the six-sided shape of snowflakes, the rectangular sides called the primary prism face, and a cut across alternate hexagonal apices called the secondary prism face. This contribution discusses results both from equilibrium-growth and from cutting-edge, nonlinear spectroscopic techniques. Equilibrium growth shows that – contrary to common belief – the stable ice-water interfaces consists of prism and pyramidal faces – diagonal cuts between prism and basal faces - not the expected basal face. A statistical model will be presented that accounts for this result.  There are two hexagonal motifs in the basal face. Electron backscatter diffraction orientation distribution plots correlated with etching images definitively connect one of these to the hexagonal shape of a snowflake. This result has important implications for the molecular level configuration of the prism faces. The surface vibrational spectroscopy sum frequency generation (SFG) shows that the molecular configuration results in unique interactions on each of these faces. SFG results support an ice model consisting of extended, cooperative motion and beyond-bonding-partner determination of hydrogen bond strength.

Many faces of ice: Molecular view of growth and interactions

2019 Fall National Meeting

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