Volume 204, 2017

Probing the interplay between geometric and electronic structure in a two-dimensional K–TCNQ charge transfer network

Abstract

Scanning tunnelling microscopy (STM), low energy electron diffraction (LEED), ultraviolet and soft X-ray photoelectron spectroscopy (UPS and SXPS) have been used to characterise the formation of a coadsorption phase of TCNQ and K on Ag(111), while the normal incident X-ray standing waves (NIXSW) technique has been used to obtain quantitative structural information. STM and LEED show that an ordered incommensurate phase is formed in which the K atoms are surrounded by four TCNQ molecules in a ‘windmill’ motif, characteristic of other metal/TCNQ phases, in which the nominal TCNQ : K stoichiometry is 1 : 1. UPS and SXPS data indicate the TCNQ is in a negatively-charged state. NIXSW results show that the carbon core of the TCNQ is essentially planar at a height above the Ag(111) surface closely similar to that found without coadsorbed K. In the presence of TCNQ the height of the K ions above the surface is significantly larger than on clean Ag(111), and the ions occupy sites above ‘holes’ in the TCNQ network. NIXSW data also show that the N atoms in the molecules must occupy sites with at least two different heights above the surface, which can be reconciled by a tilt or twist of the TCNQ molecules, broadly similar to the geometry that occurs in bulk TCNQ/K crystals.

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
06 Mar 2017
Accepted
31 Mar 2017
First published
31 Mar 2017
This article is Open Access
Creative Commons BY license

Faraday Discuss., 2017,204, 97-110

Probing the interplay between geometric and electronic structure in a two-dimensional K–TCNQ charge transfer network

P. J. Blowey, L. A. Rochford, D. A. Duncan, D. A. Warr, T.-L. Lee, D. P. Woodruff and G. Costantini, Faraday Discuss., 2017, 204, 97 DOI: 10.1039/C7FD00093F

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements