Abstract
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 = 1, 1, 2, 3 were observed. All observed IPSs showed the dispersions with effective masses of . The 2PPE intensity of the lowest IPS ( = 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.
- Received 16 December 2013
- Revised 23 March 2014
DOI:https://doi.org/10.1103/PhysRevB.89.155303
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