Physics of HREELS
As mentioned above HREELS involves an inelastic scattering process on a surface. For those processes the conservation of energy as well as the conservation of momentum’s projection parallel to the surface hold:
E are energies k and q are wave vectors and G denotes a reciprocal lattice vector. One should mention at this point that for non perfect surfaces G is not in any case a well defined quantum number, what has to be considered when using the second relation. Variables subscripted with i denote values of incident electrons those subscripted with s values of scattered electrons. “||” denotes parallel to the surface.
For the description of the inelastic scattering processes due to the excitation of vibrational modes of adsorbates different approaches exist. The simplest approach distinguishes between regimes of small and large scattering angles:
Read more about this topic: High Resolution Electron Energy Loss Spectroscopy
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