Use of specific functionalised tips with STM: a new identification method of ester groups and their molecular structure in self-assembled overlayers.
The influence of chemical modification of scanning tunnelling microscopy tips on image contrast is studied. This technique is applied to the identification of an ester functional group, hardly visible otherwise. Self-assembled overlayers of wax esters [CH3-(CH2)14-CO-O-(CH2)15-CH3], adsorbed at the interface between highly oriented pyrolitic graphite and a solution of phenyloctane, are imaged. The gold tips used are chemically modified by 4-mercaptobenzoic acid and 4-mercaptotoluene. The stability of the ordered overlayers formed facilitates the reproducible set of images with submolecular resolution. This allows the identification of the layer regular structure and of other features within molecules, which can be unambiguously related to the fingerprints of the COO bond. Moreover, we are interested in finding evidence of molecular motions observed at domain boundaries.
Volcke
Cedric
C
University of Namur (FUNDP), Laboratoire de Spectroscopie Moléculaire de Surface rue de Bruxelles, Namur, Belgium.
Simonis
Priscilla
P
Durant
François
F
Thiry
Paul A
PA
Lambin
Philippe
P
Culot
Christine
C
Humbert
Christophe
C