Quantal Nuclear Motions in Condensed H-Bonded Systems
Vendredi 19 septembre 2014 14:00
- Duree : 1 heure
Lieu : Amphi Chadwick, ILL - 6 rue Jules Horowitz - Grenoble
Orateur : Carla ANDREANI (Department of Physics
Università gli Studi di Roma ”Tor Vergata”, I)
Even at room temperature, quantum mechanics plays a major role in determining the quantitative behavior of light nuclei, changing significantly the values of physical properties such as the heat capacity. However, other observables appear to be only weakly affected by nuclear quantum effects (NQEs) : for instance, the melting temperatures of light and heavy water differ by less than 4 K. Recent theoretical work has attributed this to a competition between intra and intermolecular NQEs, which can be separated by computing the anisotropy of the quantum kinetic energy tensor. The principal values of this tensor change in opposite directions when ice melts, leading to a very small net quantum mechanical effect on the melting point.
This talk reviews experimental observation of NQEs, achieved by measuring the hydrogen and deuterium momentum distributions n(p) in light, heavy water and ice using Deep Inelastic Neutron Scattering (DINS). Direct Measurement of Competing Quantum Effects in the Melting of Heavy Water supplemented by a theoretical analysis is also presented, showing that the anisotropy of the quantum kinetic energy tensor can also be captured for heavier atoms such as oxygen.
Contact : tellier@ill.fr
Discipline évènement : (Physique)
Entité organisatrice : (ILL)
Nature évènement : (Séminaire)
Evènement répétitif : (General ILL Seminar - College 7)
Site de l'évènement : Polygone scientifique
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