Probing dynamics at interfaces: options for neutron and X-ray spectroscopy

Inelastic neutron and X-ray scattering experiments on surfaces and interfaces are a challenging topic in modern physics. Particular interest arises regarding the surfaces and interfaces of soft matter and biological systems. We review both neutron and X-ray spectroscopic techniques with a view to their applicability to these samples. We discuss the different methods, namely neutron three-axis, backscattering and spin-echo spectroscopy as well as X-ray photon correlation spectroscopy (XPCS), in the context of planar lipid membrane models as an example. By a combination of the different methods, a large range in momentum and energy transfer is accessible.