Atypical charge redistribution over a charge-transfer monolayer on a metal
Journal article, 2013
We report an atypical charge distribution in a highly ordered monolayer of sodium (Na) and tetracyanoquinodimethane (TCNQ) on a Au(111) surface. Na atoms incorporated in the charge-transfer layer donate their 3s electron to the lowest unoccupied orbital of the TCNQ acceptor. A fingerprint of such a TCNQ anion is observed in scanning tunneling spectroscopy as a zero-bias peak characteristic of the Kondo effect. Spatial maps of the Kondo resonance surprisingly reveal that it appears most intense on top of the Na sites. Supported by density functional theory simulations, we interpret this peculiar charge distribution pattern as originating from the extension of the singly occupied molecular orbital beyond the molecular backbone, and cloaking the Na cations. We further suggest that this deformation of molecular orbitals is a consequence of the electrostatic potential landscape of the polar Na-TCNQ layer.
Author
T. R. Umbach
Freie Universität Berlin
I. Fernandez-Torrente
Freie Universität Berlin
M. Ruby
Freie Universität Berlin
F. Schulz
Freie Universität Berlin
C. Lotze
Freie Universität Berlin
R. Rurali
Institute of Material Science of Barcelona (ICMAB)
Mats Persson
Chalmers, Applied Physics, Materials and Surface Theory
J. I. Pascual
Basque Foundation for Science (Ikerbasque)
Freie Universität Berlin
K. J. Franke
Freie Universität Berlin
New Journal of Physics
1367-2630 (ISSN)
Vol. 15 083048Subject Categories
Physical Sciences
DOI
10.1088/1367-2630/15/8/083048