Regensburg 2002 – wissenschaftliches Programm

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O: Oberflächenphysik

O 4: Oberfl
ächenreaktionen (I)

O 4.7: Vortrag

Montag, 11. März 2002, 12:45–13:00, H43

CONTRIBUTION OF LONG JUMPS IN THE DIFFUSION OF LARGE MOLECULES — •Michael Schunack, Troll Rene Linderoth, Federico Rosei, Erik Lægsgaard, Ivan Stensgaard und Flemming Besenbacher — Institute of Physics, University of Aarhus, DK-8000 Aarhus C, Denmark

We have studied the diffusion of two organic molecules, HtBDC and DC, on Cu(110) by time-lapse STM. A new and simple method to reveal contributions of multiple-site jumps in the surface diffusion is presented. The method is based on the fundamental, statistical relation between the mean square displacement and the hopping rate, and the results are supported by Monte Carlo simulations.

We find that long jumps, spanning multiple lattice spacings, play a surprisingly dominating role in the diffusion of these molecules - the root mean squared jump lengths are as large as 3.9 and 6.8 lattice spacings for DC and HtBDC, respectively. Moreover, the activation energies from the Arrhenius analysis differ significantly. Our results constitute a novel and important demonstration of the possibility of tailoring molecules to obtain particular diffusion properties.