A New Phase of Hydrogen at High Pressure
- Event time: 1:00pm
- Event date: 6th February 2012
- Speaker: Ross Howie (Formerly School of Physics & Astronomy, University of Edinburgh)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
The behavior of hydrogen at very high pressures is still poorly understood due to the limitations imposed on conventional experimental techniques. Currently, only three solid phases of hydrogen and deuterium (l I, II and III) are known, with studies limited to low temperature optical measurements. We have recently used Raman and visible transmission spectroscopy to investigate dense hydrogen (deuterium) up to 310 (275) GPa at 300K, conditions previously inaccessible. We not only for observe the phase transformation from I-III, previously only observed at low temperatures, but a further transition at 220 GPa to an unobserved phase, IV. Analysis of the Raman spectra suggests a peculiar graphene-like structure for phase IV, consisting of a mixture of both atomic and molecular layers. This result not only has important consequences for the hydrogen phase diagram, but also provides a gradual route to the long sought after insulator-metal transition.
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..