Inelastic incoherent neutron scattering study of D2O and H2O ice VIII in the range 2–140 meV

Computing analysis of lattice vibrations of ice VIII

“…26 Kolesnikov et al considered that the peak at the frequency of 494 cm À1 in the Raman data represents a weak peak at 484 cm À1 instead of the sharp peak at 443 cm À1 in his neutron data. 27 He speculated that the vibration mode of the peak 443 cm À1 , which is the le sharp peak in our work, does not contribute to the Raman spectrum. We can conrm the speculation by computing outcomes.…”

“…Two typical sharp peaks in libration region are observed in INS spectrum. 14,27 The frequencies of two distinct peaks are 443 cm À1 and 548 cm À1 . They are observed in our results at 503 cm À1 (PDOS)/502 cm À1 (normal modes) and 561 cm À1 (PDOS)/580 cm À1 (normal modes), with numbers of blueshi.…”

“…Measurements of the vibrational spectrum of ice VIII have been studied in the past. 14,[26][27][28][29] However, some of the assignments in ice VIII vibrational spectrum remain tentative and phenomenal due to difficulties to analyse theoretically. By using the CASTEP code, a rst-principles DFT method, we develop a new approach to theoretically investigate the lattice vibrations of ice VIII.…”

An inelastic incoherent neutron scattering study of water in small-pored zeolites and other water-bearing minerals

“…The inelastic neutron spectrum, measured by Kolesnikov et al 70 and compared to other ice spectra by Li et al, 43 has three translational bands at 14.7, 20.7, and 26.7 meV and two, possibly three librational bands at 55.0 meV, a weak shoulder at 61.4 meV, and 68.0 meV. The librational bands for Ice VIII appear similar to those in natrolite or apophyllite, albeit shifted and are supposed to be due to the presence of restoring forces for the three librations from the local tetrahedral geometry of the Ice VIII.…”

“…This is in contrast to the zeolites measured by Fuess and co-workers 36 and to ice Ih 42 but is similar to that observed in the ordered ice VIII 43,70 and Ice II. 43 The spectra can be divided up according to the number of cations which are adjacent to the water molecule: natrolite and apophyllite with two, and wairakite, bikitaite, and scolecite with one.…”