Brillouin spectroscopic studies of a crystal grain boundary region in ice Ih

Brillouin spectroscopy has been used to study the local acoustic properties of the crystal grain boundary region in a naturally formed bicrystalline sample of ice Ih at - 16°C. Spectra from the boundary region show a distinct and unexpected asymmetry $\text{in the frequency shifts}$ of the upshifted versus the downshifted longitudinal Brillouin components.