Electron Scattering from Surface Excitations

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Abstract
Surface modes play an important role in a solid's response to external disturbances. A charged particle on approaching or leaving the surface may suffer inelastic scattering owing to its coupling with these modes. The scattering rate is calculated in the Born approximation for two instances: (i) in metals, where the surface modes are plasma oscillations and (ii) in dielectrics, with optical surface phonons. For electrons in a parabolic band with energy of the order of a few electron volts, it is found that on traversing the sample, the probability of scattering is of order 1. Furthermore, this probability is highly anisotropic. These findings strongly suggest that this scattering effect should be incorporated in the analysis of energy or spatial distribution of charged-particle probes, at least in the low-energy regime.