Figure 9
Peak shift (top) and peak width (bottom) of Ti 1s photoelectrons, observed as a function of XFEL power. Both the peak shift and the peak width are determined by means of a least-squares fitting procedure. The dashed line in the upper figure is an exponential fit to the measured shifts. The shaded area represents the space-charge-induced kinetic energy bandwidth calculated by the mean-field model.  [article HTML]