Low-energy molecular vibrations investigated by inelastic scattering of He atoms

Low-frequency molecular vibrations in the energy regime relevant for thermodynamical properties (< 24 meV or 200 cm−1) are important for a variety of fields, including molecular dynamics simulations of large molecules and physical properties of polymers. Here we present a novel approach for determining the energy of these modes by scattering thermal energy He atoms off molecular monolayers physisorbed on solid substrates. The merits of the new approach will be demonstrated for the case of different n-alkanes.