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|Title: ||Nanoscale surface modification studied by reflection anisotropy spectroscopy|
|Authors: ||Lane, Paul David|
|Supervisor(s): ||Cole, Jamie|
|Issue Date: ||26-Nov-2009|
|Publisher: ||The University of Edinburgh|
|Abstract: ||The development and control of nanoscale properties is a major goal in science and
technology; for the development of such technologies it is important that there are
experimental techniques which allow the monitoring of development processes in
real time and in a range of environments. With this in mind much effort has been
invested in the development of surface sensitive optical probes. One such technique,
reflection anisotropy spectroscopy (RAS), has been applied successfully to a number
of different problems since its development in the mid 1980’s.
RAS as a surface specific technique is very sensitive to small changes to surface
morphology, electronic structure and molecular orientation. This makes RAS a
useful technique to study nanoscale changes occurring at surfaces and it is applied
here to three such systems, in an attempt to develop a better understanding of both
the systems and the technique.
Surface defects arising from thermal processing and etching of the sample are
considered and are found to have a significant effect on both the electronic structure
and the morphology of the surface. The time and temperature dependences of the
RAS signatures allow the monitoring of surface dynamic processes.
The deposition of a monolayer of adsorbate molecules onto the surface allows a new
interface to be created. Monitoring the evolution of this surface during deposition
provides information about both the substrate surface and the adsorba te covered
surface; a theoretical framework has been outlined to show how the sources of
anisotropy from multiple thin film layers combine to give a RAS signal.
Azimuth dependent RAS (ADRAS) is known to provide information on surface
symmetry and can be used to determine molecular orientation. There are also a
number of other angles which affect the RA spectrum from a sample. A tilted
molecule causes a breakdown in surface symmetry; this work shows how such an
effect can be observed.|
|Sponsor(s): ||Engineering and Physical Sciences Research Council (EPSRC)|
surface sensitive optical probes
reflection anisotropy spectroscopy
Azimuth dependent RAS
|Appears in Collections:||Physics thesis and dissertation collection|
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