Molecular diffusion on surfaces: insights from neutron scattering
Dr. Peter Fouquet
Institut Laue-Langevin, Grenoble
17:15 - 18:15 Tuesday 22 January 2019 TUG P2 The interactions between molecules and condensed matter surfaces have fascinated researchers since the beginning of modern physics, because of the dramatic changes of the physical and chemical properties that occur when molecules and surfaces are in contact. But despite enormous technological successes we have to admit that our description of the physics of surface adsorbed molecules is still very sketchy, especially when dynamics are involved.
If we want to develop an accurate theoretical framework of surface diffusion of molecules, we need to investigate diffusion processes on molecular length scales, which requires experimental and calculational methods that deliver sub-nanometer spatial resolution at nanosecond time scale. One of the few spectroscopy techniques that fulfill these characteristics is quasi-elastic neutron scattering. Although, neutron scattering does not naturally provide the required surface sensitivity, we will show that a wide range of 2D materials exist, where a high specific surface area favours the use of neutron scattering. Our recent studies have provided surprisingly simple new models for the viscosity of adsorbed aromatic models [1-3] and insight on the dynamics of hydrogen in carbon based hydrogen storage and catalyst materials [4].
[1] H. Hedgeland et al., Nature Phys. 5, 561 (2009); E. Bahn et al., Phys. Chem. Chem. Phys. 16, 22116 (2014). [2] I. Calvo-Almazan, E. Bahn et al., Carbon 79, 183 (2014). [3] I. Calvo-Almazan, et al., J. Phys. Chem. Lett. 7, 5285 (2016). [4] E. Bahn et al., Carbon 98, 572 (2016).
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