On functional groups in STM images
of self-assembled monolayers
C. Volcke1*, C. Humbert3, P. Simonis1, P. Lambin2, C. Culot1, P. A. Thiry1
1 Laboratoire Lasers et Spectroscopies (LLS)
2 Laboratoire de Physique du Solide (LPS)
University of Namur - FUNDP, rue de Bruxelles, 61, B-5000 Namur (Belgium)
3 Laboratoire de Chimie Physique, Université Paris-Sud 11, CNRS, Bâtiment 201 Porte 2, 91405 Orsay (France)
* Corresponding author.
Received: 30 March 2006; revised version accepted: 18 June 2006
The influence of the tip modification on the contrast of a Scanning Tunnelling Microscopy (STM) image is investigated. This innovative technique makes it possible to identify the molecular organisation inside self-assembled monolayers (SAMs). Moreover, the observed contrast variations, between two different tip modifications, highlight functional groups position and orientation. In situ treatment of modified tips allows to switch contrast enhancement on and off.
Keywords: Scanning tunnelling microscopy; Self-assembly; Fatty acids; Alkanethiol; Solid-liquid interfaces.