Rotational Excitations in Solid Hydrogen
Lead Research Organisation:
University of Edinburgh
Department Name: Sch of Physics and Astronomy
Abstract
The lowest pressure phase of solid hydrogen comprises a hexagonally close packed structure of molecular hydrogen. X-ray and neutron studies can detect the mean nuclear position, but the orientational behaviour is more complicated. Raman spectroscopy at the lowest pressures, shows that the molecules adopt free rotor behaviour. However when pressure increases the identification of the single rotational levels becomes more complicated, as these low frequency bands significantly broaden. This project aims to develop the theory for the Raman signal from an inhibited quantum rotor. Comparing the predicted spectra with experimental data will provide new insight into the nature of the solid phases of hydrogen under pressure.
Organisations
People |
ORCID iD |
| Graeme Ackland (Primary Supervisor) | |
| Peter Cooke (Student) |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509644/1 | 01/10/2016 | 30/09/2021 | |||
| 1941676 | Studentship | EP/N509644/1 | 01/09/2017 | 31/08/2021 | Peter Cooke |
| Description | At low temperatures and high pressures hydrogen molecules condense to form solid phases. The precise crystal structure of these solid phases remains unknown. This is largely due to the quantum nature of the hydrogen molecule. As the molecule is only composed of two single proton nuclei, the molecule itself behaves as a quantum object and therefore has a deloclised molecular wavefunction. Characterising these molecular wavefunctions is extremely challenging from both an experimental and theoretical standpoint. One experimental technique that provides some information about the molecular wavefunction is Raman spectroscopy. As one of the key findings of this award we have developed a modeul to theoretically predict Raman spectra for hydrogen molecules and therefore elucidate key characteristics of the molecular wavefunction at a range of temperatures and pressures. By comparing such a model directly to experimental results for the first time we have been able to uncover a range of previously unreported behaviourof condensed phases of hydrogen, through a more detailed analysis of the experiment. |
| Exploitation Route | The next steps would be to expand to clusters of molecules to investigate the effects of local correlation in the high pressure phases. |
| Sectors | Chemicals,Electronics |
| Description | Support for the UKCP consortium |
| Amount | £471,671 (GBP) |
| Funding ID | EP/P022561/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 04/2017 |
| End | 06/2021 |