TBPP molecules on copper surfaces: a low temperature scanning tunneling microscope investigation

A detailed low temperature scanning tunneling microscope investigation of the intramolecular conformations of individual porphyrin-based molecules adsorbed on different copper surfaces is presented. Depending on the substrate geometry, the molecules show different orientations on the surface and different internal configurations. While on the Cu(I 1 1) surface the molecule lies flat on the surface, on Cu(I 00) its legs are oriented nearly perpendicular to the substrate. On Cu(2 11) an intermediate situation takes place. The molecule lies flat on (I I I) nanofacets, but other configurations are found with one leg rotated out of the substrate plane. Accurate theory-experiment comparisons allow to precisely determine the conformation of the molecule in the different cases. (C) 2001 Published by Elsevier Science B.V.