Probing High-Barrier Pathways of Surface Reactions by Scanning Tunneling Microscopy
M. Dürr,12*
A. Biedermann,13
Z. Hu,1
U. Höfer,2
T. F. Heinz1
The ability of scanning tunneling microscopy to probe
the pathways of thermally activated high-barrier surface processes is frequently limited by competing low-barrier processes that can confuse
measurement of the true initial and final configuration. We introduce
an approach to circumvent this difficulty by driving the surface
process with nanosecond laser heating. The method is applied to
determine the pathway of recombinative desorption in the H/Si(001)
system. The observed configuration of dangling bonds after laser
heating reveals that the desorbed hydrogen molecules are not formed on
single dimers, but rather from neighboring silicon dimers via an
interdimer reaction pathway.
1 Departments of Physics and Electrical
Engineering, Columbia University, New York, NY 10027, USA.
2 Fachbereich Physik und Zentrum für
Materialwissenschaften, Philipps-Universität Marburg, D-35032
Marburg, Germany.
3 Institut für Allgemeine
Physik, Vienna University of Technology, A-1040 Vienna,
Austria.
*
To whom correspondence should be addressed. E-mail:
duerr{at}physik.uni-marburg.de
