title: Structural and collisional relaxations in liquids and supercritical fluids.
abstract: The dynamic structure factor S(Q,omega) of both associated (water and ammonia) and simple fluids (nitrogen and neon) has been determined by high-resolution inelastic x-ray scattering in the 2-14 nm(-1) momentum transfer range. A line-shape analysis with a generalized hydrodynamic model was used to study the involved relaxation process and to characterize its strength and time scale. We observe that in the liquid phase such a process is governed by rearrangements of intermolecular bonds, whereas in the supercritical region it assumes a collisional nature.
authors.affiliation: European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble, Cedex, France.
authors.forename: F
authors.initials: F
authors.lastname: Bencivenga
authors.forename: A
authors.initials: A
authors.lastname: Cunsolo
authors.forename: M
authors.initials: M
authors.lastname: Krisch
authors.forename: G
authors.initials: G
authors.lastname: Monaco
authors.forename: L
authors.initials: L
authors.lastname: Orsingher
authors.forename: G
authors.initials: G
authors.lastname: Ruocco
authors.forename: F
authors.initials: F
authors.lastname: Sette
authors.forename: A
authors.initials: A
authors.lastname: Vispa