Atypical charge redistribution over a charge-transfer monolayer on a metal
Artikel i vetenskaplig tidskrift, 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.


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

Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)

Mats Persson

Chalmers, Teknisk fysik, Material- och ytteori

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 083048