Phys. Rev. Lett. 78, 4410 (1997)
B. C. Stipe, M. A. Rezaei, and W. Ho
Laboratory of Atomic and
Solid State Physics and Materials Science Center, Cornell University, Ithaca,
New York 14853
S. Gao, M. Persson, and B. I. Lundqvist
Department
of Applied Physics, Chalmers University of Technology, S-412 96 Göteborg,
Sweden
The tunneling current from a scanning tunneling microscope was used to image and dissociate single O2 molecules on the Pt(111) surface in the temperature range of 40 K to 150 K. After dissociation, the two oxygen atoms are found one to three lattice constants apart. The dissociation rate as a function of current was found to vary as $I^{0.8\pm0.2}$, $I^{1.8\pm0.2}$, and $I^{2.9\pm0.3}$ for sample biases of 0.4, 0.3, and 0.2 volts, respectively. These rates are explained using a general model for dissociation induced by intramolecular vibrational excitations via resonant inelastic electron tunneling.
