title: Selective internal manipulation of a single molecule by scanning tunneling microscopy.
abstract: We have studied the adsorption of the polyaromatic molecule 1,4"-paratriphenyldimethylacetone, which we have nicknamed Trima. The originality of this linear molecule is that it was designed and synthesized to have two functionalities. First, chemisorb itself to the surface by its two ends rather like a bridge. Second, the central part of the molecule could then be rotated by injecting electrons with the tip of the scanning tunneling microscope (STM). The length of the molecule corresponds exactly to the spacing between five dimers in a row on the Si(100)-2 x 1 surface. We found that the molecule adsorbs as expected on the clean silicon surface by using complementary STM and synchrotron radiation studies. Manipulation of individual molecules with the STM tip showed selective internal modifications that were highly voltage dependent. These manipulations were found to be compatible with an electronic excitation of the pi-pi* transition of the molecule.
authors.affiliation: Laboratoire de Photophysique Moléculaire, CNRS, UPR 3361, Bâtiment 210, Université de Paris-Sud, 91405 Orsay, France.
authors.forename: Laetitia
authors.initials: L
authors.lastname: Soukiassian
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Mayne
authors.forename: Geneviève
authors.initials: G
authors.lastname: Comtet
authors.forename: Lucette
authors.initials: L
authors.lastname: Hellner
authors.forename: Gérald
authors.initials: G
authors.lastname: Dujardin
authors.forename: André
authors.initials: A
authors.lastname: Gourdon