Angular straggling associated with fluctuations in charge state of the projectile in grazing ion-surface scattering

We have studied the angular straggling of a few keV ions scattered off metal surfaces at grazing scattering condition. The angular straggling of scattered particles is large when the charge state of the particle fluctuates significantly in the surface region. The important physical parameters responsible for the angular straggling are the particle induced density of states and the rate of change of the energy of the atomic level with distance from the surface. An implication for the mechanism underlying skipping motion is discussed. (orig.)