Why is Stair case effect in XPS?

Answer 1

The staircase effect shown on spectrum chart, represent elasticity processes. The very high rates are part if the low energy secondary electron.

Answer 2

The staircase effect in X-ray photoelectron spectroscopy (XPS) is caused by the step-like energy levels in an XPS spectrum, which are due to the discrete energy levels at which electrons are ejected from different atomic orbitals. This effect can make it difficult to accurately determine the binding energies of elements in a sample, especially if there is overlap between different elements' energy levels.