Figure 1. Variations of the electronic band structures of monolayer graphene near the K point with increasing sodium coverage.

(a) Atomic structure and first Brillouine zone of monolayer graphene. (b) ARPES intensity map of the pristine monolayer graphene along the k_y direction. (c–g) ARPES intensity maps of the sodium-adsorbed monolayer graphene along the k_y direction. In (b–g), the dispersions (white lines) were extracted from the EDC peak positions (see Supplementary Figure S2a), and the blue lines are EDCs obtained at the K point. (h) MDCs at the E_F of the ARPES maps in (b–g).