▎ 摘　　要

The charge transfer rates of a localized excited electron to graphene monolayers with variable substrate coupling have been investigated by the core hole clock method with adsorbed argon. Expressed as charge transfer times, we find strong variations between similar to 3 fs (on graphene "valleys" on Ru(0001)) to similar to 16 fs (quasi-free graphene on SiC, O/Ru(0001), or SiO2/Ru). The values for the "hills" on Gr/Ru and on Gr/Pt(111) are in between, with the ratio 1.7 between the charge transfer times measured on "hills" and "valleys" of Gr/Ru. We discuss the results for Gr on metals in terms of hybridized Ru-C orbitals, which change with the relative Gr-Ru alignment and distance. The charge transfer on the decoupled graphene layers must represent the intrinsic coupling to the graphene empty pi* states. Its low rate may be influenced by processes retarding the spreading of charge after transfer.