When: Friday, 10th October (2014), 15:00h
Place: Facultad Ciencias, Module 0, Conference Room (307).
Speaker: Gerhard Meyer, IBM Research – Zurich Laboratory – Zurich, Rüschlikon, Switzerland.
Ultrathin insulating films on metal substrates are unique systems to use Scanning Tunneling Microscopy(STM)/Atomic Force Microscopy (AFM) to study the electronic and structural properties of single atoms and molecules, which are electronically only weakly coupled to the metallic substrate. STM permits the direct imaging of molecular frontier orbitals and in combination with atomic/molecular manipulation allows the study of elementary processes related to charge state control, molecular switching and electrical contact formation [1]. Detailed structural information can be obtained by AFM which leads to the direct imaging of the molecular geometry [2]. This allows to investigate the adsoption height and tilt of molecules [3], the bond order of individual bonds [4], and to determine the chemical structure of natural products. High resolution AFM imaging is based on specially functionalized tips, whose role in AFM imaging will be discussed. Finally it will be shown that Kelvin Probe Force Microscopy (KPFM) can map the local contact potential difference with submolecular resolution reflecting the intramolecular charge distribution [5].
References:
- J. Repp G. Meyer, S. Paavilainen, F. E. Olsson, M. Persson, Science 2006, 312, 1196.
- L. Gross, F. Mohn, N. Moll, P. Liljeroth, G. Meyer, Science 2009, 325, 1110.
- B. Schuler et al., Phys. Rev. Lett. 2013, 111, 106103.
- L. Gross et al., Science, 2012, 337, 1326.
- F. Mohn, L. Gross, N. Moll,G. Meyer, Nature Nanotechnology 2012, 7, 227.
