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A. Riss, S. Wickenburg, L. Tan, H. Tsai, Y. Kim, J. Lu, A. Bradley, M. Ugeda, K. Meaker, K. Watanabe, T. Taniguchi, A. Zettl, F. Fischer, S. Louie, M. Crommie:
"Imaging and Tuning Molecular Levels at the Surface of a Gated Graphene Device";
ACS Nano, 8 (2014), 6; 5395 - 5401.

Gate-controlled tuning of the charge carrier density in graphene
devices provides new opportunities to control the behavior of molecular
adsorbates. We have used scanning tunneling microscopy (STM) and spectros-
copy (STS) to show how the vibronic electronic levels of 1,3,5-tris(2,2-
dicyanovinyl)benzene molecules adsorbed onto a graphene/BN/SiO
2
device can
be tuned
via
application of a backgate voltage. The molecules are observed to
electronically decouple from the graphene layer, giving rise to well-resolved
vibronic states in d
I
/d
V
spectroscopy at the single-molecule level. Density
functional theory (DFT) and many-body spectral function calculations show that
these states arise from molecular orbitals coupled strongly to carbon

hydrogen rocking modes. Application of a back-gate voltage allows switching
between di
ff
erent electronic states of the molecules for
fi
xed sample bias.

graphene . organic molecules . vibronic levels . scanning tunneling microscopy . scanning tunneling spectroscopy . density functional theory . GW self-energy