It is the aim of the proposal to investigate the presence and strength of an induced magnetic polarization in Py/Pt spin pumping heterostructures (Py=permalloy, Ni80Fe20) at the Pt L-edges. We have experimental evidence from broadband (2 – 40 GHz) ferromagnetic resonance (FMR) experiments that the increase of the FMR linewidth broadening in Py/Pt spin pumping heterostructures can be gradually suppressed by inserting thin Al spacer layers. However, as pointed out before chemical intermixing going hand-in-hand with an induced magnetic polarization of the Pt is a common concern for these types of functional interfaces. Thus, the investigation of an induced polarization of the Pt by means of L-edge XMCD is the method of choice [1]. It is known that Pt in direct contact with Fe exhibits a clear induced polarization [1]. A decrease of the XMCD signal with increasing Al spacer thickness can allow to correlate induced polarization with increased spin pumping efficiency.