▎ 摘　　要

Image potential states (IPSs) on monolayer, bilayer, and trilayer graphene epitaxially grown on SiC(0001) have been studied by time- and angle-resolved two-photon photoemission (2PPE) spectroscopy. The free-electron-like dispersions of even and odd symmetry IPSs with a quantum number of n = 1(+), 1(-), 2, 3 were observed. All observed IPSs showed the dispersions with effective masses of m* = 1.0 +/- 0.1m(e). The 2PPE intensity of the lowest IPS (n = 1(+)) was attenuated with an increasing number of graphene layers. The time-resolved 2PPE measurements revealed that these IPSs have significantly shorter lifetimes, suggesting a coupling of IPSs with electronic states in the buffer layer and the SiC substrate.