Stochastic effect in grazing ion surface scattering

The energy distribution of scattered ions is determined by the trajectory and the stochastic effect. In this paper, we discuss the stochastic effect, which originates from the stochastic nature of electronic excitations, and derive a simple relation between the energy loss and the energy straggling associated with the stochastic effect (stochastic energy straggling). For the Firsov model of the inelastic energy loss, the stochastic energy straggling can be calculated directly from the magnitude of the energy loss. We also discuss the ratio of the stochastic to the trajectory energy straggling obtained from recent experiments. (orig.)