Determination of the absorption constants μ for HOPG for linearly polarized light incident with p-geometry. Using the procedure described in the text, manipulated TEY spectrum η (left axis of ordinates) is interpreted as the energy function of the absorption constant μ (right axis of ordinates). Open circles show the measured η. Filled symbols correspond to different constant values of the creation efficiency M = 1/∊. The inset shows in more detail the π-resonance peak, where differences are most pronounced. It is apparent that if the mean creation energy ∊ is increased, the problematic saturation of the measured yield at the resonance peak is appropriately compensated. An increase of ∊ corresponds to a reduction of the ratio of secondary to primary electrons.