Lineshapes, shifts and broadenings in dynamical X-ray photoelectron spectroscopy

We describe in detail a model that can be used to estimate the X-ray photoelectron spectroscopic data of surfaces when a time varying bias or a modulation of the electrical properties of the surface is applied by external stimulation, in the presence of a neutralizing electron beam. Using the model and spectra recorded under periodic sample bias modulation, certain electronic properties related to charging dynamics of the surface can be estimated. The resulting technique is a non-contact impedance measurement technique with chemical specificity. Typical behavior of spectra under a square wave bias is given. Alternative modulation schemes are investigated, including small-signal square wave modulation, sinusoidal modulation and modulation of sample resistivity under fixed bias.