Revisiting the Probing Depths of Soft X-ray Absorption Techniques by Constant Initial State Photoemission Experiments

We have recently performed accurate constant initial state (CIS) Al 2p photoemission experiments on Al films covered with layers of amorphous Ge of variable thickness, using synchrotron radiation in a variable photon energy range 100–1100 eV at the BEAR beamline at Elettra. Experiments were performed within the framework of a larger research effort aimed to obtain accurate and reliable measurements of the photoelectron mean free path (MFP) at variable kinetic energy and ultimately of the probing depth of the total electron yield and total fluorescence yield (TEY, TFY) techniques. Present MFP results are compared with previous experiments and simulations, improving our present knowledge of the MFP curve in amorphous germanium and opening new experimental possibilities for accurate measurements of the probing depth.