Abstract
Approximately 50 years of inelastic scattering studies of noble gases are reviewed to illustrate the main advances achieved in the understanding of the THz dynamics of simple systems. The gradual departure of the spectral shape from the hydrodynamic regime is discussed with an emphasis on the phenomenology of fast (sub-ps) relaxation processes. This review shows that relaxation phenomena in noble gases have an essentially collisional origin, which is also revealed by the parallelism between their characteristic timescale and the interatomic collision time. Additionally, recent THz spectroscopy results on noble gases at extreme thermodynamic conditions are discussed to illustrate the need for a revision of our current understanding of the supercritical phase.
Highlights
The study of the collective molecular dynamics of liquids and glassy materials has been a vibrant field of research since the dawn of modern science
The purpose of this review is to provide a short overview of THz spectroscopy studies of S(Q,ω) in noble gases and in particular, to discuss the insight they shed on fast relaxation phenomena
This brief review shows that THz studies on simplest systems as noble gases have, across the years, evidenced a rather complex behavior
Summary
The study of the collective molecular dynamics of liquids and glassy materials has been a vibrant field of research since the dawn of modern science. S(Q,ω) is probed by generating density fluctuations on a target sample through the collision with a beam of particle-waves, i.e., photons or neutrons. The shape of S(Q,ω) is exactly predicted within these two limits and essentially unknown in between, i.e. in the so-called mesoscopic region, corresponding to Q’s and ω’s matching the inverse of intermolecular separations and cage oscillation frequencies, respectively. Investigations of this region may unravel fundamental aspects of molecular motions and mutual interactions in disordered systems and can be ideally performed by X-ray (IXS) and neutron (INS) scattering techniques, as well. Due to the lack of rigorous theoretical predictions, our understanding of the dynamics of disordered systems at mesoscopic scales is often limited to a phenomenological analysis of experimental and computational results
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
