Proton ordering in Antarctic ice observed by Raman and neutron scattering

Analysis of the Raman spectra of Antarctic ice showed that a second-order phase transition from the proton-disordered phase to a proton-ordered phase takes place at Ti=237 K (Ti; ice temperature in the ice sheet) in the Antarctic ice sheet. We discovered that the incoherent inelastic neutron scattering spectra of both ice XI (with the proton-ordered arrangement) and Dome–Fuji (DF) Antarctic ice (Ti=213 K) have a sharp peak at 79 meV in the librational region, but the peak of ice Ih is much lower. This neutron measurement confirmed that the proton-ordered arrangement exists in DF ice.