Large-distance quantum confinement passing through a single-layer graphene

Constructing quantum corrals on a surface is an effective strategy for precise regulation of surface electronic states. Nevertheless, this strategy has only been demonstrated to work when the corrals are adsorbed directly on coinage metals. Herein, we report large-distance electronic state confinement passing through a single-layer graphene (SLG) by an extended molecular adlayer. Although the adlayer is 6.7 Å away from Cu(111) with the graphene sheet in between, the corrals defined by the adlayer can still trap the free electron gas of the Cu surface effectively, lifting the dispersive band of Cu. The electron donated from Cu substrate to SLG is demonstrated to migrate above the SLG surface instead of accumulating at the Cu-SLG interface. The physisorbed molecular layer sharpens the dispersion of graphene electronic states. Our results open new possibilities for the design of hybrid electronic devices and graphene modification.