The interaction of Xe and Xe + K with graphene

We have investigated the electronic properties of monolayer graphene with adsorbed layers of xenon or potassium, or a combination of the two. The formation of the first Xe layer is characterized by a dipole polarization which is quenched by a second Xe layer. By comparing K on Xe on graphene to K on bare graphene, we determine the K contribution to trigonal warping and mass renormalization due to electron-phonon coupling. The former is found to be small but significant, while the latter is shown to be negligible. Thus, previously determined values of electron-phonon coupling for K on graphene are shown to be intrinsic to doped graphene and not determined by the proximity of K ions to the graphene.