Fourth Annual Niels Bohr International Academy Workshop-School on ESS Science: Opening a new window into surface interactions by combining inelastic neutron scattering and reflectometry with molecular dynamics
Many chemical reactions are initiated at the surface, i.e. at the first few atomic layers of a substance, by means of chemical or electrostatic interactions, quantum phenomena or thermal agitation. X-ray and neutron reflectometry measurements provide information that is related to the manner in which molecules bind to a surface, while inelastic neutron scattering gives insight into the motions of the molecules, as well as the response of the internal vibrations of the molecule, to the interaction with the surface. The information that can be extracted from both of these experimental methods is complementary and directly related to the energy landscape of molecular binding of surface reactions.
Applications of reflectometry cover all types of thin film growth, self-assembly, structure and interactions of molecules at surfaces and interfaces. Exemplary are switchable materials that undergo structural changes in response to external stimuli (chemical, mechanical, electrical or electromagnetic) as well as solid thin films, multilayered structures and interfacial effects, particularly in magnetic materials.
Of equal importance is the fact that the characteristic frequencies of most motions of surface-bound molecules and intermediate reactive species can be observed by inelastic neutron scattering (INS) and light scattering methods. The increasing structural complexity of many large systems of current interest has the consequence that simple phenomenological models can no longer adequately describe the resulting complex dynamical phenomena. New computational tools based on ab-initio density functional or molecular mechanics based molecular dynamics simulations have become essential for the elucidation of dynamical phenomena as they relate to real life functionality.
A combination of elastic and inelastic scattering methods, such as reflectometry, quasielastic neutron scattering (QENS) and INS offers the possibility to gain a detailed understanding of relationships between structural and dynamic properties and thus ultimately the function of materials.
Our workshop is intended to be a forum of discussion of how the use of X-ray and neutron reflectometry tells us about the binding of molecules to a surface and of how the characteristic frequencies of motions of surface-bound molecules can be detected by inelastic neutron scattering and light scattering spectroscopies, and finally, how such experimental results can be interpreted by molecular dynamics simulations.
The needs and interests of students with different backgrounds will be addressed with discussion on the use of these experimental methods in soft matter and magnetism. Results of studies using polarized neutron reflectometry (PNR), INS and inelastic X-rays scattering (INX) will be at the core of those tutorials. Here we focus on understanding how electrons organize themselves in solids to produce the amazingly wide range of phenomena encountered in a wide range of systems.