title: Crystal-like high frequency phonons in the amorphous phases of solid water.
abstract: The high frequency dynamics of low-density (LDA) and high-density (HDA) amorphous ice and of cubic ice ( I(c)) has been measured by inelastic x-ray scattering in the 1-15 nm(-1) momentum transfer ( Q) range. Sharp phononlike excitations are observed, and the longitudinal acoustic branch is identified up to Q = 8 nm(-1) in LDA and I(c) and up to 5 nm(-1) in HDA. The narrow width of these excitations is in sharp contrast to the broad features observed in all amorphous systems studied so far. The "crystal-like" behavior of amorphous ices, therefore, implies a considerable reduction in the number of decay channels available to soundlike excitations which is interpreted as a sign of low local disorder.
authors.affiliation: Institut Laue-Langevin, F-38042 Grenoble Cedex, France.
authors.forename: H
authors.initials: H
authors.lastname: Schober
authors.forename: M M
authors.initials: MM
authors.lastname: Koza
authors.forename: A
authors.initials: A
authors.lastname: Tölle
authors.forename: C
authors.initials: C
authors.lastname: Masciovecchio
authors.forename: F
authors.initials: F
authors.lastname: Sette
authors.forename: F
authors.initials: F
authors.lastname: Fujara