Why do we have more number of electrons contributing to noise at higher B.E as compared to lower B.E.
What my understanding says that inelastic collided electron cause background but why it is increasing with increase in B.E.
has this something to do with addition of all noises, as the measurement progress??
You are right - it has to do with inelastic scattering of electrons. If the electron originating from the O 1s core level undergoes an inelastic collision on the way to the surface it will be detected with somewhat lower kinetic energy, meaning that it will contribute to the spectrum at higher binding energy than all other O 1s electrons that make it without collisions.
This is true for every core level hence, the background level increases with increasing binding energy.
The background in XPS is non-trivial in nature and results from all those electrons with initial energy greater than the measurement energy for which scattering events cause energy losses prior to emission from the sample. The zero-loss electrons constituting the photoelectric peak are considered to be the signal above the background approximation. (c) CASA XPS 2013-2014
Thank you all for the answers.
But I have one question, Why measured spectra shows step like increment in background intensity (while moving from lower B.E. to higher B.E. direction)
I would like to add that the inelastic scattering processes are random and multiple and therefore the background is continuum.
I suspect you are using a Non-Mono Mg X-ray source. If you look at the new PHI handbook and compare mono to non-mono surveys, you can see the Non-mono has higher BG.
If you are working with transition metals (eg Fe, Ni, Co) then they have multiple Auger signals that also add to BG in the High BE region.
Thank you all for the helping me in understanding this concept. :)
The spread in the peak of inelastic scattering is more from the bound electrons compared to the free electrons.
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