Raman scattering at the proton ordering phase transition in ice crystal

The proton ordering I-h-XI phase transition at 72K in KOH doped ice single crystal was studied by Raman Spectroscopy. The spectral changes related to the proton ordering phase transition in the translational region were obser ved reproducibly. In XI ordered phase the intensity of the peak at 230cm(-1 ) becomes strong and two new peaks appear at 237cm(-1) and 324cm(-1), while the broad component between 250cm(-1) and 310cm(-1) becomes weak. The new lines at 237cm(-1) and 324cm(-1) are assigned as the LO-modes which are enh anced by the depolarization field due to the ferroelectric ordering of wate r molecules in ice.