Issue |
Europhys. Lett.
Volume 50, Number 2, April II 2000
|
|
---|---|---|
Page(s) | 202 - 208 | |
Section | Condensed matter: structure, mechanical and thermal properties | |
DOI | https://doi.org/10.1209/epl/i2000-00255-3 | |
Published online | 01 September 2002 |
Single-particle mean kinetic energy in low-density
supercritical
1
Consiglio Nazionale delle Ricerche (CNR) - Roma, Italy
2
Istituto Nazionale per la Fisica della Materia (INFM), UdR
“Tor Vergata”
Via della Ricerca Scientifica 1, 00133 Roma, Italy
3
Dipartimento di Fisica, Università degli Studi di Roma
“Tor Vergata”
Via della Ricerca Scientifica 1, 00133 Roma, Italy
Received:
17
May
1999
Accepted:
31
January
2000
We report novel results from inelastic neutron scattering measurements
at very high momentum transfer, 122 Å
performed in
supercritical 4He, along two very low-density isochores (
nm-3 and
nm-3) in the temperature
range 5–30 K. The experimental data have been analysed
within the framework of the plane-wave Impulse Approximation and the
temperature dependence of the single-particle mean kinetic energy has
been derived. It is found that this quantity deviates from the
classical behaviour in the whole temperature range explored, showing
the quantum nature of this system even for these very low-density
isochores, the lowest ever experimentally explored. For the higher
density, the temperature evolution of the single-particle mean kinetic
energy has also been derived using a path-integral Monte Carlo
code. These quantum simulation results, as well as those already
available for the low-density isochore, are in good agreement with the
experimental data. It is pointed out that, at these densities, the
temperature dependence of the mean kinetic energy is consistent with
an anharmonic behaviour of 4He induced by the hard-core component
of the interatomic potential.
PACS: 67.20.+k – Quantum effects on the structure and dynamics of
nondegenerate fluids (e.g., normal phase liquid ) / 61.12.Ex – Neutron scattering techniques (including small-angle scattering)
© EDP Sciences, 2000
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