It is doubly refracting, uniaxial, optically positive with very small birefringence. Ih is centered around 840 cm -1 . The proton-ordered phases show distinct narrow peaks in their infrared and Raman spectra. From infrared and Raman spectroscopy on the ice phases, much has been learned about the intermolecular coupling mechanism, lattice dynamics, and the properties of H-bonds. For electromagnetic waves with frequencies from 5 to 300 MHz the loss of energy by absorption in ice is sufficiently small that they can penetrate large ice masses great distances.
Ice is a viscoelastic material with a nonlinear flow law.
When shear stress is applied to a single crystal of ice, it undergoes plastic shear strain easily parallel to the basal plane, which is perpendicular to the hexagonal c-axis. In other directions the stress needed to produce plastic shear deformation is much higher. When polycrystalline ice is subjected to stress, it immediately deforms elastically, followed by transient creep, and finally steady viscous flow called secondary creep is reached. For high stresses in excess of 400 kPa the creep curve accelerates which is called tertiary creep. Values of A, Q, and n depend to some extent on the grain size, grain orientation distribution, and impurity content of the polycrystalline material.