Babak Haghighi - Dept. of Physics, Faculty of Science, Islamic Azad University, mashhad Branch, mashhad,Iran
Nader Haghighi - Faculty of Science, Islamic Azad University, Qum Branch, Qum,Iran

Differential cross-section of inelastic scattering and loss function of fast charged particles in a two- dimensional electron gas(2DEG) on surface Helium crystals are calculated at low temperatures, taking into account the localization of electrons at impurity atoms. The contribution collective excitations of the electron gas to the scattering cross-section and loss function is considered.. Localization of electrons leads to a decrease in the frequency of two-dimensional plasmons. Consequently, the plasma loss lines in the energy spectrum of electrons passing through a two- dimensional electron gas are displaced towards lower frequencies and are broadened. Numerical estimates are obtained for Helium crystals at the boundary between liquid Helium and vapor Helium

plasma waves, magnetoplasma waves, 2DEG, Helium crystals