We have investigated the moiré Bloch bands of photoexcited electrons in image potential states on graphene covered Ir(111) surfaces using high-energy-resolution angle-resolved two-photon photoemission spectroscopy. An energy gap of approximately 20 meV at the $\overline{\mathrm{K}}$ point of the moiré Brillouin zone is resolved. The band structure is well reproduced by density functional theory (DFT) combined with the embedded Green's function technique. A simplified periodic potential model, whose spatial distribution shows close agreement with the DFT results, also describes the system well. These findings demonstrate that the electronic band structure of photoexcited states can be engineered solely via moiré potential modulation. This opens another avenue for excited-state band engineering and the design of ultrafast optoelectronic functionalities in moiré-engineered materials.

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• Band gap
• Charge dynamics
• Surface reconstruction
• Surface states
• Graphene
• Density functional calculations
• Two-photon photoelectron spectroscopy