Incoherent inelastic neutron scattering measurements on ice XI; the proton-ordered phase of ice I h doped with KOH

We measured incoherent inelastic neutron scattering spectra of ice I _h and ice XI; the proton-ordered phase of I _h. The proton ordering in our sample of ice XI was 83%. At 27 and 36 meV we observed peaks in ice I _h and ice XI, have been considered as the evidence for the model of the two kinds of hydrogen. These peak intensities in ice XI were, however, the same as those in ice I _h. The similarities are inconsistent with the model. Furthermore, we found width of the libration mode in ice XI was much smaller than that in ice I _h.