title: Quantum effects in the dynamics of He probed by inelastic x-ray scattering.
abstract: Quantum effects in the teraherz dynamics of supercritical 4He have been studied as a function of both density rho and temperature T; they have been characterized through their effects on the second and third spectral moments of the dynamic structure factor S(Q, omega), measured by the inelastic x-ray scattering (IXS) technique. The IXS spectra were collected in the low-Q region below and around the position of the first diffraction peak Q(m), i.e., in a range relatively unusual in this kind of investigation. The measured spectral moments clearly show a departure from their high-T classical expected values. We observe, moreover, that the amplitude of quantum deviations increases slightly with increasing density. This experimental method allows us to extract, even in a region where the dynamics still maintains a collective character, such typical single particle properties as the mean atomic kinetic energy.
authors.affiliation: European Synchrotron Radiation Facility, Boîte Postal 220, F-38043 Grenoble Cedex, France.
authors.forename: R
authors.initials: R
authors.lastname: Verbeni
authors.forename: A
authors.initials: A
authors.lastname: Cunsolo
authors.forename: G
authors.initials: G
authors.lastname: Pratesi
authors.forename: G
authors.initials: G
authors.lastname: Monaco
authors.forename: F
authors.initials: F
authors.lastname: Rosica
authors.forename: C
authors.initials: C
authors.lastname: Masciovecchio
authors.forename: M
authors.initials: M
authors.lastname: Nardone
authors.forename: G
authors.initials: G
authors.lastname: Ruocco
authors.forename: F
authors.initials: F
authors.lastname: Sette
authors.forename: F
authors.initials: F
authors.lastname: Albergamo