Electron doping of graphene has been extensively studied on graphene-supported surfaces, where the metallicity is influenced by the substrate. Herewith we propose potassium adsorption on free-standing nanoporous graphene, thus eluding any effect due to the substrate. We monitor the electron migration in the x* downward-shifted conduction band. In this rigid band shift, we correlate the spectral density of the x* state in the upper Dirac cone with the associated plasmon, blue-shifted with increasing K dose, as deduced by electron energy loss spectroscopy. These results are confirmed by the Dirac plasmon activated by the C 1s emitted electrons, thanks to spatially resolved photoemission. This crosscheck constitutes a reference on the correlation between the electronic x* states in the conduction band and the Dirac plasmon evolution upon in situ electron doping of fully free-standing graphene.
Tuning the Electronic Response of Metallic Graphene by Potassium Doping / Marchiani, D.; Tonelli, A.; Mariani, C.; Frisenda, R.; Avila, J.; Dudin, P.; Jeong, S.; Ito, Y.; Magnani, F. S.; Biagi, R.; De Renzi, V.; Betti, M. G.. - In: NANO LETTERS. - ISSN 1530-6984. - 23:1(2023), pp. 170-176. [10.1021/acs.nanolett.2c03891]