| AVS 64th International Symposium & Exhibition | |
| Tribology Focus Topic | Wednesday Sessions |
| Session TR+AS+HI+NS+SS-WeA |
| Session: | Molecular Origins of Friction |
| Presenter: | Yuan Zhang, Argonne National Laboratory |
| Authors: | Y. Zhang, Argonne National Laboratory S. Khadka, Ohio University B. Narayanan, Argonne National Laboratory A. Ngo, Argonne National Laboratory Y. Li, Ohio University B. Fisher, Argonne National Laboratory L. Curtiss, Argonne National Laboratory S. Sankaranarayanan, Argonne National Laboratory S.W. Hla, Argonne National Laboratory |
| Correspondent: | Click to Email |
Mechanical properties of molecules adsorbed on materials surfaces are increasingly vital for the applications of molecular thin films as well as for the fundamental understanding of quantum friction. Here, we employ atomic/molecular manipulation schemes to investigate mechanic and symmetry dependent lateral diffusion processes of individual molecules on various substrates using a combined scanning tunneling microscope (STM) and q+ atomic force microscopy system at low temperature and in ultrahigh vacuum environment. Lateral force measurements of individual sexiphenyl, an oligomer type molecule, exhibits an interesting friction behavior originated from the symmetry of the molecule-substrate system. We found ~160% increase in the lateral force during the diffusion of the molecule across a Ag(111) surface depending on the long molecular axis alignment on the surface. A comparison of the shape and symmetry dependent molecular diffusion process is realized by manipulating cobalt-porphyrin molecules on aAu(111) surface. The results are in full agreement with molecular dynamic simulations. In addition, we will also discuss atomic and molecular level force measurement using an STM tip, which opens simultaneous electronic, structural and force measurements at the single atom and molecule level.