Specific Process Knowledge/Characterization/XPS/XPS technique: Difference between revisions
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; Transport towards the vacuum | ; Transport towards the vacuum | ||
: The inelastic mean free path of the photoelectrons is very short. The information carried by the photoelectrons will therefore quickly degrade as they collide inelastically and loose part of their energy. This means that only photoelectrons originating from the ~10 topmost atomic layers of the sample contribute to the signal - in this way making XPS extremely surface sensitive. The tail of former photoelectrons with non-specific energy is called the background. From inside the sample the electrons must pass the socalled work function in order to escape into the vacuum. | : The inelastic mean free path of the photoelectrons travelling inside a solid is very short in this energy range. The information carried by the photoelectrons will therefore quickly degrade as they collide inelastically and loose part of their energy. This means that only photoelectrons originating from the ~10 topmost atomic layers of the sample contribute to the signal - in this way making XPS extremely surface sensitive. The tail of former photoelectrons with non-specific energy is called the background. From inside the sample the electrons must pass the socalled work function in order to escape into the vacuum. | ||
; Detection in the analyzer | ; Detection in the analyzer | ||
: In the analyzer the electrons are separated according to the kinetic energy by two concentric spheres held at some potential. By playing on the acceptance angle of the entrance/exit slits of the analyzer one can tune the energy resolution with the parameter called pass energy. Subsequently detected by the spectrometer, the number of electrons may be plotted as a function of energy thus making up an XPS spectrum. | : In the analyzer the electrons are separated according to the kinetic energy by two concentric spheres held at some potential. By playing on the acceptance angle of the entrance/exit slits of the analyzer one can tune the energy resolution with the parameter called pass energy. Subsequently detected by the spectrometer, the number of electrons may be plotted as a function of energy thus making up an XPS spectrum. | ||