1. Organisation of undecane (organic molecular) layer, silicon
regions and electrolyte interface and bulk.
of silicon by covalent attachment of organic molecules is currently
an area of intensive research because of its applications for bio-functionalising
We have a method
for covalently attaching organic molecular monolayers directly to
the atomically-flat Si(111) surface of silicon (Figure 1). An electrical
impedance spectroscopy methodology we have developed allows the
characterisation of the dielectric and conductance properties of
various substructural layers in this system, including details of
the depletion region established in the silicon close to the surface.
Variations in these dielectric substructure with applied DC potential
allowed us to determine the potential dependence of the thickness
of this depletion region in the silicon and also monitor electrostrictive
effects in the organic layers chemically bonded to the silicon surface.
2. Thickening of one of the substructural layers of the silicon
depletion regions with increasing V.
measurements were supplemented with low angle X-ray reflectometry
and X-ray photoelectric spectroscopy (XPS) measurements of the monolayer
to obtain further structural information, chemical composition and
molecular density data.
3. Thicknesses of the alkane (hydrocarbon) region consistent
with alkane electro-mechanical properties
It is hoped
to extend the experiments to include bimolecular lipid bilayer membranes
“tethered” to silicon substrates via covalently attached
molecular tethers. Such systems would provide a new research tool
for studies in biophysics and would have applications in drug screening.
This work is
a collaboration between the School of Physics (Biophysics), School
of Biotechnology and Biomolecular Sciences (UNSW) and Neutron Scattering
Böcking, Terry Chilcott, Hans Coster, Kevin Barrow and Michael