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Abstract:

The plasmon excitations of the degenerate free-electron gas in the surface space-charge region of InSb have been studied using high-resolution electron-energy-loss spectroscopy. Semiclassical dielectric theory simulations of the energy-loss spectra have been performed using the hydrodynamic and Boltzmann-Mermin models. While both analyses include the effects of temperature, conduction band nonparabolicity, spatial dispersion and collisional damping, the hydrodynamic model is not able to quantitatively reproduce the experimental spectra at higher excitation wave vectors. The measured spectral shapes are only accurately reproduced when collisionless plasmon damping is included explicitly using the Boltzmann-Mermin dielectric function. © 2006 The American Physical Society.