Phonon stiffening induced by copper intercalation in monolayer graphite on Ni(111)
Institute of Physics, St. Petersburg State University - St. Petersburg, 198904 Russia
2 Fachbereich Physik, Freie Universität Berlin Arnimallee 14, D-14195 Berlin, Germany
Accepted: 7 August 1998
The intercalation of copper underneath a graphite monolayer (MG) formed on Ni(111) has been investigated by means of HREELS, Auger spectroscopy and LEED. The softening of the graphite phonon modes in the case of the MG/Ni(111) system, caused by a strong interaction with the Ni substrate, is removed after intercalation of copper. The corresponding phonon dispersion curves are very similar to those of bulk graphite and the C(KVV) Auger spectra resemble very much those of classical graphite intercalated compounds. This demonstrates that the observed stiffening is a consequence of a smaller charge transfer from the copper atoms into the π-states of graphite.
PACS: 63.20.Dj – Phonon states and bands, normal modes, and phonon dispersion / 63.22.+m – Phonons in low-dimensional structures and small particles / 79.20.Fv – Electron impact: Auger emission
© EDP Sciences, 1998