Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)
O 35.89: Poster
Tuesday, March 12, 2013, 18:15–21:45, Poster B1
Two-photon photoemission studies of graphene on Ir(111) — •D. Nobis1, D. Niesner1, Th. Fauster1, M. Kralj2, M. Petrović2, P. C. Yeh3, S. Y. Hong3, W. Jin3, J. Dadap3, and R. M. Osgood3 — 1Universität Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen, Germany — 2Institut za fiziku, Bijenička 46, HR-10000 Zagreb, Croatia — 3Columbia University, New York, NY 10027, USA
Graphene can be grown on Ir(111) with high quality by decomposition of hydrocarbons [1]. The band structure of this system has been studied with various techniques [2,3]. We have used two-photon photoemission (2PPE) to study the image-potential states of graphene on Ir(111). Using monochromatic 2PPE (photon energies 3.99 − 4.86 eV) and bichromatic 2PPE (pump pulse 4.77 eV, probe pulse 1.59 eV) we observe two n=1 image-potential bands. The main peak agrees with previous data [3]. The weaker second band has a slightly larger binding energy and effective mass.
We discuss possible origins of the second band: (a) Splitting in odd and even bands with respect to the graphene layer [4]. (b) Umklapp bands or (c) localized states due to the moiré structure of graphene on Ir(111) [5].
[1] van Gastel, R. et al., Appl. Phys. Lett. 95 (2009) 121901
[2] Kralj, M. et al. Phys. Rev. B 84 (2011) 075427
[3] Niesner, D. et al., Phys. Rev. B 85 (2012) 081402(R)
[4] Bose, S. et al., New J. of Physics 12 (2010) 023028
[5] Armbrust, N. et al., Phys. Rev. Lett. 108 (2012) 056801