(Color) Pictures of two ice crystal slices taken through crossed polarizers: (a) Crystal showing multiple domains with clearly visible grain boundaries. The step pattern in the upper right quadrant is due to hoppering from growth of a grain boundary. (b) A single-crystal specimen. The entire domain remains extinct as the crystal is rotated between cross polarizers, indicating that the axis is within 1° of the line of sight.
(Color) Conoscopic images of single-crystal ice samples. (a) The cross is located at the center of the concentric rings indicating that the axis is parallel to the viewing direction, perpendicular to the interface. (b) The cross is shifted to the upper-right corner indicating a miscut of about 5°. (The images are produced on a dark background due to the crossed polarizers; the dark background has been removed in order to show the image structure.)
(Color) Etching pattern on the basal face clearly showing hexagonal features. The image corresponds to a or area. Each feature originates where a screw dislocation emerges at the surface. This image was taken on poor quality ice. SFG spectra were typically run on samples with a dislocation density less than .
SFG spectra of ice with three polarization combinations: (star), (half-diamond), and (half-circle) at . Inset: magnified to show structure.
Survey of the temperature dependence of the SFG signal: (star), (triangle), and (circle). (a) polarization and (b) polarization. Note that the free-OH (open star) is not drawn to scale; it is approximately 100 times weaker than the hydrogen-bonded region.
The peak intensity at in the polarization combination vs .
(Color online) Signal as a function of infrared beam energy at the entrance window; polarization is . Spectra were run in the following order: (blue triangle), (green circle), (magenta forward triangle), (orange star), and return to (black diamond). Raising the infrared intensity from scales the intensity proportional to the infrared energy. The signal saturates and even diminishes from indicating saturation and nonlinearity. Nonlinearity continues with a beam energy of . Returning to after exposure to demonstrates that the higher energy infrared beam has introduced irreversible damage to the surface.
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