observation of a molecular junction by high-energy x-ray reflectometry
Michael Lefenfeld, Julian Baumert, Eli Sloutskin,
Ivan Kuzmenko, Peter Pershan, Moshe Deutsch, Colin Nuckolls, Benjamin M.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF
THE UNITED STATES OF AMERICA
103 (8), February, 2541-2545 (2006)
We report a direct angstrom resolution measurement of the structure
of a molecular-size electronic junction comprising a single (or a double)
layer of alkyl-thiol and alkyl-silane molecules at the buried interface between
solid silicon and liquid mercury. The high-energy synchrotron x-ray measurements
reveal densely packed layers comprising roughly interface-normal molecules.
The monolayer's thickness is found to be 3-4 angstrom larger than that of
similar layers at the free surfaces of both mercury and silicon. The origins
of this and the other unusual features detected are discussed in this article.
Measurements of the bilayer junction with an applied potential did not show
visible changes in the surface normal structure.