Lithium metal was deposited from an alkali getter source (SAES Getters) by resistively heating the source (7.1 A, 1.1 V) in line-of-sight of the sample at a distance of around 6 cm. Under these conditions, the Li deposition rate was around 0.04 -0.05 ML min , where a monolayer corresponds to a saturated Li layer with an approx. Li layer thickness d of 2.5 Å. The layer thicknesses d were calculated using the relation d = -ln(Id/I0)  ( cos  (I0: substrate peak intensity before deposition, Id: intensity after deposition, the inelastic mean free path (IMFP) in the film material at the given electron energy, : emission angle with respect to the surface normal), assuming a homogeneous layer by layer growth. Here we used electron inelastic mean free paths (IMFPs) λ of 46 Å in Li and of 35 Å in the IL at kinetic energies of ∼ 1200 eV (C1s graphite peak) for the calibration of the deposited amounts of Li and IL. The latter signal was also used to calibrate the binding energy (BE) scale.