Phonons and Structures in Rubidium and Oxygen at High Pressure
Rubidium metal and oxygen are normally best kept well apart! In this talk I will describe the results of two recent experiments high-pressure phases of these two elements. In rubidium, we have made the first inelastic x-ray scattering study of the longitudinal-acoustic (LA) phonons in a composite structure in an element, and show that two LA phonon branches are observed, which can be attributed to separate lattice vibrations in the host and guest subsystems. The observations for the one-dimensional guest chains can be reproduced quantitatively with the monatomic linear chain model used to introduce the concept of phonon dispersion in solid-state textbooks. In the second experiment, recently published in Nature, we have determined the structure of the red epsilon-phase of oxygen found between 10 and 100GPa. The structure is both entirely new and extremely elegant.
This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..