Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 100: Graphene: Adsorption, Intercalation, Doping (organized by O)

TT 100.8: Talk

Thursday, April 3, 2014, 17:45–18:00, WIL C107

Tuning the van der Waals Interaction of Graphene with Molecules by Doping — •Felix Huttmann¹, Antonio Javier Martinez-Galera¹, Nicolae Atodiresei², Vasile Caciuc², Stefan Blügel², and Thomas Michely¹ — ¹II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany — ²Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich, 52428 Jülich, Germany

Strong n-doping of graphene on its epitaxial substrate can be introduced via intercalation of highly electropositive elements such as Cs and Eu, and has recently been shown to lead to reduced binding energy for electropositive, ionic adsorbates [1].

Here, we explore tuning of graphene's van der Waals (vdW) interaction with adsorbates via doping. Employing an all in-situ surface science approach, we find by scanning tunneling microscopy and thermal desorption spectroscopy a significantly higher binding energy on n-doped as opposed to undoped graphene for the vdW-bonded molecules benzene and naphthalene. This is just opposite to the case of electropositive, ionic adsorbates. Based on the model character of these simple pi-conjugated molecules [2], we propose that the strength of the van der Waals interaction is modified by doping. The experimental results are compared to density functional calculations, including van der Waals interactions.

References:

[1] S. Schumacher et al., Nano Lett. 13, 5013 (2013)

[2] S. D. Chakarova-Käck et al., Phys. Rev. Lett. 96, 146107 (2006)