Identifying trapping desorption in gas–surface scattering

Classical trajectory simulations are used to determine the energy transfer distribution function P(Ef) for Ne-atoms scattering off the n-hexylthiolate self-assembled monolayer (SAM)/Au{1 1 1} surface. The form of P(Ef) depends on the angles at which it is measured. Though trapping desorption is insignificant for this system, backward scattering and scattering normal to the surface give rise to a unimodal P(Ef) in excellent agreement with the Boltzmann distribution. Forward scattering at large polar angles is bimodal with a Boltzmann-like component. These simulation results show that a Boltzmann component in P(Ef) does not necessarily correspond to a trapping desorption intermediate.