Nanostructuring Cu Surfaces Using Custom-Designed Molecular Molds R. Otero, † F. Rosei, †,§ Y. Naitoh, † P. Jiang, ‡ P. Thostrup, † A. Gourdon, ‡ E. Laegsgaard, † I. Stensgaard, † C. Joachim, ‡ and F. Besenbacher* ,† Interdisciplinary Nanoscience Center (iNANO), Center for Atomic-scale Materials Physics (CAMP), and Department of Physics and Astronomy, UniVersity of Aarhus, DK-8000 Aarhus C, Denmark, and CEMES - CNRS, 47 Rue J. MarVig, Toulouse, France Received October 9, 2003; Revised Manuscript Received November 5, 2003 ABSTRACT By means of STM imaging and manipulation, we show that violet Lander (VL) molecules (C 108 H 104 ) act as nanoscale templates at the Cu(110) step edges, creating nanostructures to which the VLs are anchored. These nanostructures are longer and sometimes wider than those created by the related single Lander (SL) molecules due to the slightly different shape and size of the VL molecules. These results illustrate the possibility of controlling the formation of nanostructures on a surface on the atomic scale by means of a rational molecular design. The interaction between large organic molecules and metal surfaces has recently been the subject of extensive investiga- tions. The interest in these systems stems, on one hand, from the desire to understand elementary surface processes such as adsorption and diffusion, 1-5 and on the other hand, from the potential perspective of novel applications in molecular electronics and nanomechanical devices. 6-12 To create func- tional molecular devices, it is necessary to develop an architecture for their interconnection in a planar conformation and with atomic precision. 6 When large molecules adsorb on metal surfaces, the molecule-substrate interaction may be quite complex, and molecular functionalities and confor- mations designed for molecules in the gas-phase cannot be transferred a priori to a situation where molecules are adsorbed on surfaces. For example, the surface may undergo a restructuring process in order to accommodate the mol- ecule. 4,5,7,8,13,14 Whereas the reconstructions induced by simpler adsorbates depend exclusively on their chemical nature, in the case of large organic molecules also the shape of the molecule comes into play. For instance, the molecular conformation has proven to play an important role in the chiral reconstruction induced by HtBDC on Cu(110), arising from the chirality of the lowest energy conformation of the molecule, 3,4 or in the reshaping of the step edge induced by the molecule known as single Lander (SL). 7,8 Synthetic organic chemistry permits a very flexible mo- lecular design. For example, different related molecules can be synthesized so as to preserve the main design features of a given molecular species yet allow the modification of some architectural details, such as the distance or the angles between the functional groups. The surface reconstructions induced by these modified species should therefore open a new paradigm in the control of surface morphology at the atomic scale. In this letter we investigate the rearrangement induced at the step edges of a Cu(110) surface by an organic molecule named violet Lander 15 (VL, C 108 H 104 ) and compare it with the reconstruction induced by the related single Lander molecule, which was shown before to act as a template for the fabrication of nanostructures at the Cu(110) step edges. 7,8 Both molecules consist of a polyaromatic board with four Tbp (3,5di-tert-butyl-phenyl) substituents that lift the mol- ecular board above the surface and, therefore, act as “spacer legs”. 7,15 The difference between the two species is the geometry of the board, being longer in the VL (2.5 nm) than in the SL (1.7 nm) and having a different distribution of phenyl rings with respect to their symmetry axis σ (see Figure 1a and b). Here we show that, similar to the case of the SL, the VL exploits its peculiar shape to trap diffusing Cu adatoms at the step edge, leading to the creation of nanostructures that protrude from the step edge. The mol- ecules accommodate their board on the nanostructure, while the legs rest on the lower terrace. The details, however, of the nanostructure induced by the two molecules differ: the structure induced underneath the VL is longer, and sometimes also wider, than the corresponding structures created by the SL. Comparison with theoretical calculations allows us to trace the origin of these differences back to the different molecule-substrate interactions arising from the different * Corresponding author. E-mail: fbe@phys.au.dk ² University of Aarhus. ‡ CEMES. § Present address: INRS-EMT, University of Quebec, 1650 Boul. Lionel Boulet, J3X 1S2 Varennes (QC) Canada. NANO LETTERS 2004 Vol. 4, No. 1 75-78 10.1021/nl0348793 CCC: $27.50 © 2004 American Chemical Society Published on Web 11/26/2003