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Dynamics of Low and Medium Energy Electrons Near Solid Surfaces
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Europe/Zurich
30/7-018 - Kjell Johnsen Auditorium (CERN)
Description
The interaction of electrons with solid materials is of great importance in many branches of fundamental and applied science,
for example, in electron microscopy and spectroscopy for the investigation of the structure and electronic state of solid surfaces.
The mechanism for creation and emission of slow electrons is of paramount importance for particle detection with electron multiplier devices, high energy physics accelerators and storage rings, the plasma wall interaction in a fusion reactor and the energy and charge balance of gaseous electronics such as plasma display panels. Generally speaking it is related to the energy dissipation of energetic particles moving inside a solid. A state of the art model including a detailed description of surface excitations will be presented and the connection between commonly employed numerical procedures such as the Monte Carlo Technique and its analytical counterpart,
the so called Landau_Goudsmit-Saunderson (LGS) loss function will be discussed and illustrated by means of several examples.
These include modelling of electron transport in nanostructured surfaces, the contribution of in-vacuo electron scattering to electron spectra and secondary electron–electron energy loss coincidence spectroscopy (SE2ELCS). In the latter technique correlated electron
pairs are analysed and detected. One electron of this pair corresponds to a primary electron that has lost a certain amount of
energy before being backscattered, while the second electron is liberated as a result of the energy transfer and thus provides an answer as to how the energy transfer from the primary to the secondary takes place and gives insight into the mechanism of secondary electron creation. This technique reveals i.a. what happens to the energy deposited during a supersurface scattering process when an electron in vacuum transfers energy and momentum to the solid state electrons. Application of the approaches above will be discussed for different carbon allotropes with the aim to understand the reduction of the secondary electron emission coefficient from graphite coatings for electron cloud mitigation in accelerator and particle storage systems.